Progress 10/01/16 to 09/30/17

Outputs
Target Audience:My target audience included University of California Cooperative Extension advisors, especially those with farm, environmental horticulture and integrated pest management assignments, private pest control advisors and California Department of Pesticide Registration-certified applicators, Master Gardeners, Federal, State and County ag officials and scientists as well as other representatives from agribusinesses including chemical and biological control industries, crop commodity boards, and growers. Examples of my extension efforts include invited participation to several commodity research and pest control advisor meetings where I present educational seminars. As a member of the board of directors of the Conference on Soilborne Plant Pathogens,I participatein the annual meeting organization. I also organize field days for growers, advisors and industry representatives. Furthermore, frequently I receive and respond to phone calls, emails and other messages through social media from the general public concerning plant-parasitic nematode biology, ecology, and their population management strategies. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?This project has provided training for University of California farm advisors, private pest control advisors and industry personnel who attended our field days. I mentored one Brazilian Ph.D. student who conducted some of her thesis research in my lab. Furthermore, I advised one postdoctoral researcher from Taiwan and one visiting scientist from P.R. China. How have the results been disseminated to communities of interest?I presented our results at various grower's and workgroup meetings as well as workshops (see other products). Frequently, I am asked to update the Nematode sections of the UC IPM websites. Phone calls and email inquiries provided me with further opportunities to disseminate information to my clientele. I'm also the webmaster for the California Nematology Workgroup (http://ucanr.edu/sites/CA_Nematology/). What do you plan to do during the next reporting period to accomplish the goals?Realizing that non-fumigant nematicides or biological control products will be unlikely to achieve sufficient nematode control, we are planning to combine management strategies such as plant resistance with various other tools to mitigate crop damage by root-knot nematodes. We hypothesize that early season cropping to resistant tomato or cowpeas will reduce the root-knot nematode population sufficiently to replace soil fumigants with biologicals and/or novel nematicides at seeding or plantingof a second susceptible crop.

Impacts
What was accomplished under these goals? Plant-parasitic nematodes cause more than $12 billion crop damage in the US and an estimated $150 billion worldwide. Some soil fumigants are excellent pre-plant tools in terms of efficacy against soilborne microbial and nematode pathogens. But various issues related to potential negative impacts on human health and environment as well as economic aspects are driving the search for safer, less expensive alternatives. My research group focuses on novel biologicals and conventional nematicides as well as on improved management strategies for plant-parasitic pathogens. Objective 1: A fungal strain was isolated from field soil with suspected suppressive activity against root-knot nematodes. This fungal strain was identified as Aspergillus japonicus based on morphological and molecular methods. Objective 2: Laboratory studies focused on in vitro toxicity of its fermentation broth against second-stage juveniles (J2) of Meloidogyne incognita. After two weeks growing in nutrient broth, the fungal filtrate and up to a 40-fold dilution exhibited a high mortality rate against J2 of M. incognita. The mortality rate was 100% after 6 h at 2-fold dilution, 12 h at 5- and 10-fold dilution, and 93.8% after 48 h exposure to 20-fold dilution. The nematode content was degraded and the J2 became transparent with increasing time and filtrate concentration. In a germination assay, the filtrate of the fungal strain had no effect on the germination of corn, wheat, rice, cabbage, cucumber, and tomato. The results suggested that the strain produced and excreted metabolites toxic to root-knot nematodes but without a negative effect on seed germination. Other strains of this species are known to produce various secondary metabolites including alkaloids and lipolytic enzymes during fermentation. Objective 3: Several field trials were conducted at the University of California South Coast Research and Extension Center, Tustin, CA. We evaluated various microbial and botanical biocontrol products as well as novel conventional nematicides against root-knot nematodes (Meloidogyne incognita) in cucumber and carrot trials. The treatments included mustard meal and Majestene. Mustard meal showed remarkable efficacy against nematode-caused disease symptoms at 2 tons/acre while Majestene had no effect on root galling at 4 gallons/acre. In contrast, the conventional development nematicides Nimitz and Salibro significantly reduced disease symptoms and increased marketable yield compared to the non-treated control. Objective 4: Information was disseminated at 17 events that are listed under "other products".

Publications

• Type: Journal Articles Status: Published Year Published: 2017 Citation: Mundo-Ocampo, M., J.G. Baldwin, T.J. Pereira, J.R. Camacho-Baez, A.D. Armenta-Bojorquez, M. Camacho-Haro, and J.O. Becker 2017. Occurrence of Belonolaimus in Sinaloa, Northwestern Mexico: A New Report on Distribution and Host Range. Journal of Nematology 49(1): 103113.
• Type: Journal Articles Status: Published Year Published: 2017 Citation: Becker, J.O., A. Ploeg, and J. Nunez 2017. Novel nematicides for root-knot nematode management in fresh market carrot production, 2016. Plant Management Disease Reports, Vol. 11:N026.
• Type: Journal Articles Status: Published Year Published: 2017 Citation: Ploeg, A.T., J.O. Becker, and S. Stoddard 2017. Novel nematicides to manage root-knot nematodes in California sweetpotato, 2016. Plant Management Disease Reports, Vol. 11:N027
• Type: Other Status: Published Year Published: 2018 Citation: Becker, J.O. and B. Westerdahl 2018. Onion/Garlic: Nematodes. Pp. 28-31. In: UC IPM Pest Management Guidelines: Onion/Garlic, UC ANR Publication 3453.
• Type: Other Status: Published Year Published: 2017 Citation: Becker, J.O., and B. Westerdahl 2017. Citrus: Nematodes. Pp. 183-185. In: UC IPM Pest Management Guideline: Citrus, UC ANR Publication 3441.
• Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Becker, J.O., and J. Smith Becker 2017. 25 Years After the Discovery of Sting Nematodes in California: Summary of Research and Extension Efforts. 2017 UCR Turfgrass and Landscape Research Proceedings p. 9.
• Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Becker, J.O., A. Ploeg and J. Nunez 2017. New nematicides provide effective protection against root-knot nematodes. International Carrot Conference, Bakersfield, CA. Proceedings PM-109. http://ucanr.edu/sites/test02082001/view_oral_presentation_abstracts/pest_management/
• Type: Conference Papers and Presentations Status: Published Year Published: 2017 Citation: Chen, Y. Y., H. Wu, A. Loffredo, R. Lobo, G. Tanizaki, and J.O. Becker 2017. Susceptibility of Pitahaya Species to the Southern Root-knot Nematode. American Society for Horticultural Science National Meeting. Supplement to HortScience Volume 52(9) September 2017, pp. S435-S436.

Progress 10/01/15 to 09/30/16

Outputs
Target Audience:My target audience included University of California farm, environmental horticulture and integrated pest management advisors, private pest control advisors and EPA certified applicators, Master Gardeners, State and County ag officials, researchers and other representatives from agribusinesses including chemical and biological control industries, California Department of Food and Agriculture and USDA personnel, crop commodity boards, and growers. Examples of my outreach activities include invited participation at several commodity research meetings, the organization of the combined Conference on Soilborne Plant Pathogens/Statewide CA Nematology Workshop, field days for growers, advisors and industry representatives, as well as receiving numerous phone calls from the general public concerning plant parasitic nematode issues. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?The project has provided training for University of California farm advisors, private pest control advisors and industry personnel who attended our field days. I mentored one postdoctoral researcher. How have the results been disseminated to communities of interest?I gave presentations at various grower's and workgroup meetings as well as workshops (see listed below). Frequent phone calls and email inquiries provided me with further opportunities to disseminate information to my clientele. I'm also the webmaster for the California Nematology Workgroup (http://ucanr.edu/sites/CA_Nematology/). Pitahaya Producer Day, Ventura, September 16, 2016, "Nematode Research in Dragon Fruit Production" (invited presentation). Turf & Landscape Day, September 15, 2016, AgOps, UC Riverside, "Nematicidal Protection against the Pacific shoot-gall nematode Anguina pacificae in Poa annua greens" (invited presentation). Field trial result demonstrations and discussion, UC Riverside, August 24, 2016 2016 Pitahaya/Dragon Fruit Production Seminar, San Diego County Farm Bureau, Escondido, CA August 19, 2016, "Nematode Issues for Pitahaya Production" 55th Annual Society of Nematologists Meeting/ONTA Annual Meeting, Montreal, Canada, July 17-19, 2016. Novel nematicides in processing tomato (invited Symposium presentation) Environmental Horticulture Program Team meeting, UCCE Ventura, April 18-19, 2016. "Nematodes in California turf" (presentation). 62nd Conference on Soilborne Plant Pathogens & 48th Statewide CA Nematology Workshop, Kearney Research & Extension Center, March 22-26, 2016 "Nematicides - past and future" (invited presentation). Annual California Fresh Carrot Advisory Board Research Symposium, Bakersfield, CA, March 16, 2016. "Field assessment of non-fumigant nematicides against root-knot nematodes." Association of Applied IPM Ecologists Conference, Monterey, CA, Feb 1-2, 2016. "Nematicide revival?" (invited presentation) UC Vegetable Crops Program Team Meeting, ANR Building, Davis, CA, Dec 8-9, 2015. "New crop protection products against plant parasitic nematodes." (invited presentation) Multistate Research Project meeting, W3147, "Managing Plant Microbe Interactions in Soil to Promote Sustainable Agriculture", Mission Inn, Riverside, CA, Dec 6, 2015. "Evaluation of a strain of Purpureocillium lilacinum". (presentation) First annual "Do No Harm" Workshop, UC Riverside Palm Desert Center, November 5, 2015. "The Sting Nematode, a Subterranean Invasive Species in the Coachella Valley" (presentation). 26th Annual Fall Desert Crops Workshop; El Centro, CA, Oct 29, 2015. "From suppressive soils to biological control of Heterodera schachtii" (invited presentation). What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Objective 1:Crops in northern Sinaloa, Mexico, are limited by root-knot nematodes (Meloidogyne spp.). The objective of this research was to identify nematophagous fungi in Valle del Fuerte soils where bell peppers are grown under protected conditions and susceptible to Meloidogyne spp. Soil samples were collected and processed with a sprinkling plate method. Nematophagous fungi were transferred to cornmeal agar and identifying to genus level. Objective 3: In afield trialat the South Coast Research and Extension Center, Tustin, CA,we evaluated various microbial and botanical biocontrol products as well as novel conventional nematicidesagainst root-knot nematodes (Meloidogyne incognita). The treatments included mustard meal,MeloCon (Purpureocillium lilacinum 251), and Majestene, as well as mustard meal followed by MeloCon 2 weeks later. Only mustarrd meal had a disease reducing effect. In contrast, the conventional development nematicideQ8U80 resulted in more than 95% marketable produce. Objective 4: Information was disseminated at 16 events that are listed below and under "other products".

Publications

• Type: Journal Articles Status: Published Year Published: 2016 Citation: Juan Fernando S�nchez Portillo, Gabriel Antonio Lugo Garc�a, Manuel Mundo Ocampo, �lvaro Reyes Olivas, Irma De Ley Tandingan, and J. Ole Becker 2016. Search and isolation of nematophagous fungi vs Meloidogyne spp. in northern Sinaloa, Mexico. Revista Mexicana de Ciencias Agr�colas 7:1829-1839.
• Type: Other Status: Published Year Published: 2015 Citation: Becker, J.O. 2015. Cilantro/Parsley: Nematodes. In: UC IPM Pest Management Guidelines: Cilantro and Parsley; UC ANR Publication 3476. pp. 26-27.
• Type: Other Status: Published Year Published: 2016 Citation: Westerdahl, B.B., A.T. Ploeg, and J.O. Becker 2016. Carrot: Nematodes. Pp. 38-40. In: UC IPM Pest Management Guidelines: Carrot, UC ANR Publication 3438.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Smith Becker, J., and J.O. Becker 2015. Comparative virulence of Dactylella oviparasitica strains for the control of Heterodera schachtii. 18th International Plant Protection Congress 2015, Berlin. Abstract Booklet p. 249.
• Type: Conference Papers and Presentations Status: Published Year Published: 2016 Citation: Becker, J.O., A. Ploeg, and J. Nunez 2016. Evaluation of novel nematicides for control of root-knot nematodes in processing tomato. Journal of Nematology 48:302.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Becker, J.O., L. L�ders, J. Smith Becker, and A. Ploeg 2015. Mitigation of root knot nematode damage in carrot production by a seed-delivered nematicide. 18th International Plant Protection Congress 2015, Berlin. Abstract Booklet p. 23

Progress 10/01/14 to 09/30/15

Outputs
Target Audience:My primary target audience was made up of University of California farm, environmental horticulture and integrated pest management advisors, private pest control advisors and applicators, Master Gardeners, State and County ag officials, researchers and other representatives from agribusinesses including chemical and biological control industries, California Department of Food and Agriculture and USDA personnel, crop commodity boards, and growers. Examples of my outreach activities include invited participation at several commodity research meetings, the organization of the combined Conference on Soilborne Plant Pathogens/Statewide CA Nematology Workshop, field days for growers, advisors and industry representatives, as well as receiving numerous phone calls from the general public concerning plant parasitic nematode issues. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?This program has provided training for advisors,PCAs and industry personnel whoattended our field days. I mentored an undergraduate student in one-on-one training. Furthermore I convinced the Associated Dean of our College (Ag Dean) to sponsor the participation of 10 graduate students at the Conference of Soilborne Plant Pathogens/Statewide Nematology Workshop. How have the results been disseminated to communities of interest?I gave 15 presentations at various meetings and workshops as well as two media interviews.Frequent phone calls and email inquiries provided me with further opportunities to disseminate information to my clientele. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? A key accomplishment during the past year was the discovery that the potential biological controlagent D. oviparasitica is far more common than previously known. It also appears to have a much wider host range than previously shown. Finally, efficacy of parasitism or simply stated the ability to be an effective biocontrol agent differs among strains. Objective 1. No new biocontrol agents were identified. Objective 2.Ouranalysis of H. schachtii females collected from Imperial Valley sugar beet rootsidentified D. oviparasitica in 74% of the soils. By extracting DNA directly from soil,D. oviparasiticawas found in 12 of 20 soils (60%). Objective 3.We investigated three different strains of D. oviparasitica concerning their ability to parasitize eggs and females of H. schachtii. These fungal strains originated from different hosts and geographical locations. As expected, the strains differed in growth pattern andspeed on various media as well as in parasitism. It suggests that hostpreference andability to adapt to local soil or rhizosphere/biome are key criteria for successful introduction and establishment of potential biocontrol agents.We confrmed earlier observations that peat was a suitable carrier and storage medium for this sporeless fungus. Ojective 4. This year's combined Conference of Soilborne Plant Pathogens/Statewide California Nematology Workshop was held at the University of California Campus. With nearly 100 participants, including attendees from Australia, the UK, and Japan, it wasone of the best attended meetings in recent years. The interest in soilborne diseases and their potential biological or biorational controlis increasing as chemical management options become increasingly restricted and molecular approaches are still struggling with translating them into useful products.

Publications

• Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Eberlein , C., S. Vidal, J.O. Becker and A. Westphal 2013. Population density suppression of Globodera pallida in a multi-year microplot trial with potato monoculture. Journal of Plant Diseases and Protection 120:142.
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Witte, H., J. Yang, J. Borneman, J. Smith Becker, and J.O. Becker 2014. Assessment of soils for the presence of the nematophagous fungus Dactylella oviparasitica by a PCR-based strategy. Proceedings of 6th International Congress of Nematology, Cape Town, SA, p. 49.
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Becker, J.O., and H.V. Morton 2014. Seed treatments against plant parasitic nematodes: When a little goes a long way. Proceedings of 6th International Congress of Nematology, Cape Town, SA, p. 90.
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Smith Becker, J., H. Witte, and J.O. Becker 2014. Peat as a suitable growth media and carrier for Dactylella oviparasitica. Proceedings of 6th International Congress of Nematology, Cape Town, SA, p. 240.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: S�nches-Portillo, J.F., G.A. Lugo-Garcia, M. Mundo-Ocampo, I. De Ley-Tandingan, and J. O. Becker 20014. Isolation, characterization and virulence of nematophagous fungi against Meloidogyne spp. in the north of Sinaloa, Mexico. Abstract book 47th Annual Meeting of the Organization of Nematologists of Tropical America (ONTA), Varadero, Cuba, May 18-22, 2015. pp. 105.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Smith Becker, J. and J.O. Becker 2015. Growth kinetics of Dactylella oviparasitica strains in a peat carrier. Abstract book 47th Annual Meeting of the Organization of Nematologists of Tropical America (ONTA), Varadero, Cuba, May 18-22, 2015. pp. 105-106.

Progress 10/01/13 to 09/30/14

Outputs
Target Audience: The target audience was comprised of University of California farm and horticulture advisors, private pest control advisors, State and County ag officials, scientists and other representatives from agribusinesses and biocontrol Industry, CDFA and USDA personnel, crop commodity boards, and growers. My efforts to reach those clientele include for example the Statewide Nematology Workshop, presentations at the California carrot research meeting, the California sugar beet grower's research meeting and field days for growers and industry representatives. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? I provided one-on-one training for my graduate student and for an undergraduate student from the University of Kiel (Germany) who spent 10 months in my group as part of her study-required internship. Major part of the training was related to setting up and conducting field trials. My graduate student attended also the Statewide California Workshop and the Conference on Soilborne Plant Pathogen. Both events offered opportunities for him to present his research as well as networking with faculty and students from other universities. How have the results been disseminated to communities of interest? Apart from nearly daily phone calls and email inquiries from clientele, during this reporting period I have given 14 presentations to various commodity groups, at pest control advisor meetings, and workshops. I have also given two press and radio interviews that helped to disseminate our results to a wider audience. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Root diseases are important constraints in crop production in warmer climates such as California. These problems are frequently the result of complex interrelationships among plants and their biotic/abiotic environment. Soil organisms such as fungi, bacteria, nematodes, and others play an important role in plant health and agricultural sustainability. Economic losses due to soilborne pathogens and pests including plant-parasitic nematodes are notoriously underestimated. In the US financial losses due to plant parasitic nematodes alone exceed $11 billion per year. Conventional and organic production in California, both by far the largest in the US by crop value, have considerable nematode challenges. Apart from the underlying goal of achieving a better understanding of host-parasite-antagonist interactions in naturally disease suppressive soils, my project seeks to utilize the lessons learned in developing a new generation of safe, affordable and effective tools for plant protection against nematode pests. One of the outcomes of this project has been my substantial contribution to the development of a new biorational seed-coating product that has been a breakthrough in seedling protection against plant parasitic nematodes. In the next phase we anticipate the development of products for seedling protection against plant parasitic nematodes that will utilize both biorational and biological control modules. We will continue to focus on Dactylella oviparasitica and Pasteuria spp. that are both effective hyperparasites on our economically most important plant parasitic nematodes. Objective 1 focuses on the discovery of new microorganisms for plant disease control. We tested several strains of Dactylella oviparasiticain vitro for their potential to parasitize the beet cyst nematode. There are considerable differences in their efficacy. Although this has been observed with other biocontrol agents, it is a key finding. Objective 2 addresses such strain differences. We conducted numerous experiments to determine in vitro growth at various temperatures, pH values, osmotic potential and on different media.The fungal growth rate was greatest at an osmotic potential of -0.3 MPa and decreasing osmotic potential resulted in decreasing growth.None of the strains grew at an osmotic potential of -6.3 MPa.The fungal strains grew within a temperature range from 11° to 33°C with optimum growth at approximately 25°C. Variation of media, osmotic potentials, temperatures, light regimes and use of eggs of Meloidogyne incognita as a potential growth substrate did not initiate sporulation with any of the strains. The impact of these findings is that we cannot rely on conidia as potential survival structure and inoculum source which is an important factor to consider for commercialization. Objective 3is intended to work towards the goal of developing practical tools for nematode management by combining various modules such as protective seed treatments with genetically resistant cultivars, cover crops, or biological control microorganisms. Our greenhouse and field trials have shown that seed coated abamectin, a microbial-derived natural nematicide can substantially reduce root-knot nematode-caused galling of various seeded crops. Furthermore, it reduces the early attack of fungal pathogens that often take advantage of the nematode's disease causing parasitism. Although the efficacy of the seed coating treatment is limited to a few weeks, typically currently used soil-applied nematicides do not last much longer. However, a combination of seed-coated abamectin with biocontrol organisms might extend the length of protection or improve the efficacy. Objective 4 intends to translate the research into extension activities that inform and educate stakeholders but also change often negative attitudes towards biological control approaches. In my presentations and workshops I point out that frequently we can achieve with seed-delivered abamectin the same protection against nematodes with 10-50 times less active ingredient per acre than with our current nematicide standards. In addition abamectin has no antimicrobial activity which allows its combination with bacterial or fungal biocontrol strains. Another impact of this project is that several mental barriers are or will be broken. Since abamectin seed coating has become commercially available, newer and better products are being developed. Growers will realize that for less cost equal or even more yield can be produced with less impact on the environment.

Publications

• Type: Book Chapters Status: Published Year Published: 2014 Citation: Mathews, D.M., J.O. Becker, and S. Tjosvold 2014. Plant Diseases. Chapter 13. In Newman, J. (ed) Container Nursery Production and Business Management Manual. Univ. of Calif. Agric. and Nat. Resour. Publication 3540. Richmond, CA. pp.178-200.
• Type: Book Chapters Status: Published Year Published: 2014 Citation: Becker, J.O. 2014. Citrus Pest Management: Nematodes. In: UC Citrus Production Manual, eds. L. Ferguson, E. E. Grafton-Cardwell., Univ. of Calif. Agric. and Nat. Resour. publication 3539 pp. 303-306.
• Type: Book Chapters Status: Published Year Published: 2014 Citation: Becker J.O. 2014. Plant Health Management: Crop Protection with Nematicides. In: Neal Van Alfen, editor-in-chief. Encyclopedia of Agriculture and Food Systems, Vol. 4, San Diego: Elsevier, pp. 400-407.

Progress 01/01/12 to 12/31/12

Outputs
OUTPUTS: Previously we identified various plant pathogen suppressive soils that serve us as model systems for investigating the nature, ecology and mode of action of the causal agent(s). We identified the nematophagous fungus Pochonia chlamydosporia as the likely candidate for causing the nematode population decline in a root-knot nematode-suppressive soil. We genetically characterized several strains and evaluated them for efficacy against root knot nematodes. A second nematode-suppressive location is a field at the Agricultural Operations, UC Riverside. Previously we have identified the ascomycete Dactylella oviparasitica the causal agent of a long-term sugar beet cyst nematode suppression. A series of pot experiments were performed to examine the population dynamics of the nematode and the nematophagus fungus D. oviparasitica. A literature study of related cases of cyst nematode population suppression uncovered reports describing a sterile nematophagous fungus (ARF-L) that had similar mycelium appearance and biocontrol activity against the soybean cyst nematode Heterodera glycines. These investigations at the University of Arkansas starting in the 1990s. In a collaborative study with researchers in Arkansas and Georgia, we compared in vitro growth, parasitism and genetic relatedness of the ARF-L strain with D. oviparasitica strain 50. Avicta seed coating was evaluated against the early attack of Meloidogyne spp. in several carrot field trials during 2010-2012. Furthermore we tested it in combination with various biocontrol agents. The product's active ingredients are metabolites of Streptomyces avermectinius. I extended information from these projects at the following events: W2147 Annual meeting, Mission Inn, Riverside, CA, December 7, 2012. "Management of vegetable production in root-knot nematode infested fields with biological control products"; Vegetable Crop Update Meeting, UC West Side, Five Points, 12/4/12. "Biological, biorational and conventional nematicides". CAPCA Ventura, Santa Paula, CA, 10/14/12. "New leads in plant parasitic nematode management" . Agrobusiness Nematology Training Session, UC SCREC, Irvine, CA, 10/24/12. "Evaluations of Biological Tools against Phytoparasitic Nematodes." (workshop with A. Ploeg). Progressive Farmers Meeting/UCCE, Blythe, CA, 10/18/12. "Management of plant parasitic nematodes". Plant Sciences Seminar , UC Riverside,10/17/12. "Soils suppressive to plant parasitic nematodes", Environmental Horticulture Meeting, Irvine, CA, 10/3-4/12. "A root-knot nematode in Coachella turf". Turf & Landscape Day, AgOps, UC Riverside, 9/13/12. "Studies concerning Coachella Valley rot-knot nematodes". Nematology WG, San Marino, CA, 3/20/12. "Update on current research activities." Nematology Workshop, Huntington Gardens, 3/20-22/12. "Novel nematicides in processing tomatoes." Carrot Board Meeting, Bakersfield, 3/8/12. "Evaluation of new nematicides in carrot production" PAPA, El Centro, 2/16/12. "Evaluation of novel IPM strategies". CA Sugar Beet Meeting, Holtville, CA, 1/10/12. "Novel tools for plant parasitic nematode management". PARTICIPANTS: J.O. Becker, A. Ploeg, Department of Nematology, UC Riverside, CA; J. Borneman, M. Stanghellini, Department of Plant Pathology and Microbiology, UC Riverside, CA; D.R. Jeske, Department of Statistics, UC Riverside; G. Abawi, Cornell University; D. Eastburn, University of Illinois; K. Everts, University of Maryland; J. Hao, Michigan State University; J. Parke, Oregon State University; G. Yuen, University of Nebraska; T. Paulitz, Washington State University; P. Timper, USDA-ARS, Tifton, GA; Research Specialist: J. Smith Becker, Department of Nematology, UC Riverside, CA. Post-doctoral fellows: F. S. Rocha, A. Loffredo, Department of Nematology, UC Riverside; Graduate student: J. Yang, P.M. Ruegger, University of California, Department of Plant Pathology and Microbiology, Riverside, CA, Undergraduate students: S. Benecke, Department of Statistics, UC Riverside; Collaborators: J. Nunez, UCCE Kern County, Bakersfield, CA; Partner Organizations: Members and institutions of W3147; UC South Coast Research and Extension Center, Irvine, CA; UC Kearney Research and Extension Center, Reedley, CA, UC Riverside Campus, Agricultural Operations, Riverside, CA. TARGET AUDIENCES: The main audiences include UC advisors, growers, pest control advisors, CDFA, USDA, industry, commodity personnel and other organizations that are affected by or interested in plant parasitic nematodes and other soilborne pathogens. My program provides information on natural, biorational and chemical plant disease suppression which benefit the entire spectrum of conventional and organic growers, landscapers and home gardeners including underrepresented and minority groups. My research and extension emphasis on feasible alternatives to currently used pesticides is aimed at reducing the use of hazardous materials that require strict safety standards during handling and application. These regulations are often compromised in part because of language and/or education challenges. Safe use of conventional pesticides and alternative methods will be especially important for small farms as many are operated by minorities and underrepresented groups. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Three Pochonia chlamydosporia var. chlamydosporia strains were isolated from a M. incognita-suppressive soil and genetically characterized with multiple Pochonia-selective typing methods based on analysis of beta-tubulin, rRNA internal transcribed spacer (ITS), rRNA small subunit (SSU), and enterobacterial repetitive intergenic consensus (ERIC) PCR. All strains exhibited different patterns with the ERIC analysis. Strains 1 and 4 were similar with PCR analysis of beta-tubulin and ITS. All P. chlamydosporia strains significantly reduced the numbers of nematode egg masses. This indicates castration or destruction of nematode females. Strain 4 reduced egg numbers on tomato roots by almost 50%, and significantly reduced nematode-caused root galling. In our other project, after two nematode generations, the population density of H. schachtii was determined in relation to various initial infestation densities of both D. oviparasitica and H. schachtii. Generally, higher initial population densities of D. oviparasitica were associated with lower final population densities of H. schachtii. Regression models showed that the initial density of D. oviparasitica was significant when predicting the final density of H. schachtii as well as fungal egg parasitism. We also showed that the densities of H. schachtii-associated D. oviparasitica fluctuate greatly, with rRNA gene numbers going from zero in most field-soil-collected cysts to an average of 4.24 x 10E8 in mature females isolated directly from root surfaces. Phylogenetic analysis of rRNA genes suggested that both D. oviparasitica and ARF-L belong to the same clade of nematophagous fungi. Further database search revealed similar sequences from Europe and Asia which suggests that these fungi are widely distributed. We anticipate that these findings will provide a base for the development of more effective decision models for sugar beet planting. Currently only the population density of cysts is used for planting decisions. Avicta provided consistent early season protection against root-knot nematodes in several carrot field trials during 2010-2012. Combination of Avicta with live biocontrol bacteria or fungi is possible as the a.i. has no known antimicrobial activity. In greenhouse tomato trials with M. incognita, the combination of Avicta with Pochonia chlamydosporia was superior to either treatment alone in reducing the nematode population (J2) and root galling as well as in increasing plant weight. Similar results were obtained in microplot trials with a Avicta/Pasteuria penetrans combination.

Publications

• Yang, J., A. Loffredo, J. Borneman, and J.O. Becker 2012. Biocontrol efficacy among strains of Pochonia chlamydosporia obtained from a root-knot nematode suppressive soil. Journal of Nematology 44:67-71.
• Yang, J., S. Benecke, D.R. Jeske, F. Rocha, J. Smith-Becker, P. Timper, J.O. Becker, and J. Borneman 2012. Population dynamics of Dactylella oviparasitica and Heterodera schachtii: toward a decision model for sugar beet planting. Journal of Nematology 44:237-244.
• Becker, J.O., A. Ploeg, and J. Nunez 2012. Evaluation of novel products for root knot nematode management in tomato, 2011. Plant Disease Management Report No. 6:N016.
• Smith Becker, J., J. Yang, J. Borneman, P. Timper, R.R. Riggs, and J.O. Becker 2011. Investigations into the relatedness of the nematophagous fungi Dactylella oviparasitica and ARF-L. J. Nematology 43: 228.
• Ploeg, A., J.O. Becker, and J. Nunez 2011. Integrated control of root-knot nematodes in California carrot. J. Nematology 43: 271.
• Witte, H., J. Smith Becker, and J.O. Becker 2012. In vitro growth response of Dactylella oviparasitica strain 50 to various culture media and environmental factors. J. Nematology 44: 497.

Progress 01/01/11 to 12/31/11

Outputs
OUTPUTS: Previously we have identified locations suppressive to the sugar beet cyst nematode, Heterodera schachtii and the southern root-knot nematode, Meloidogyne incognita. Pathogen-suppressive soils are not only a potential source of effective novel biocontrol agents, they also provide an opportunity to study and analyze microbiomes that keep pathogens at a low population and/or activity level. In a survey of soil samples collected from about agricultural fields in Southern California we addressed questions concerning the occurrence and distribution of such soils with activity against the sugar beet cyst nematode. Regulatory restrictions on some of the most effective pesticides against soilborne diseases have far reaching consequences for agricultural production in California. Novel chemical, biorational and biological products were tested for efficacy against root-knot nematodes in carrot and fresh tomato production. We also evaluated new system approaches to reduce the population density of root-knot nematodes (M. incognita and M. javanica) by seed meal treatment. This pre-season treatment was combined with a seed coating of microbial metabolites. Replant suppression is a disorder that often occurs when specific plant species are grown in soil that had previously supported the same or closely related plant species. This phenomenon has been recognized for more than 200 years, occurring in all of the major agricultural regions of the world on pome, stone fruits and related ornamentals. We found attempts to replant own-rooted Rosa sp. to fill the gaps in the rows of rose bushes along a scenic parkway were not all successful. Consequently we investigated potential soil-borne causes that lead to rose replant failures. Information was presented to growers, turf superintendents, Pest Control Advisors (PAPA/CAPCA/CHAPA), Master Gardeners, CDFA, USDA, industry personnel and other interested parties: Turfgrass and Landscape Institute, Rancho Cucamonga, CA, December 14, 2011. "Soil Amendments for Managing Plant Parasitic Nematodes: Theory and Practice" (invited). Annual Fall Desert Crops Workshop, El Centro, CA, November 29, 2011. "New Developments in Management of Plant Parasitic Nematodes" (invited). UCR Turf/Landscape Research Field Day 2011, UC Riverside, CA. September 15, 2011. "A new root-knot nematode in bentgrass" (invited). Society of Nematologists Annual Meeting, Corvallis, OR, July 16-21, 2011. "Relatedness of the nematophagous fungi Dactylella oviparasitica and ARF-L. (poster). Port of San Diego-UCCE IPM 5/19, 2011, Chula Vista, CA. "Do soil amendments have activity against plant parasitic nematodes" (invited). Sugar beet Research Meeting, Holtville, May 5, 2011. "Sugarbeet cyst nematode in Southern California" (invited). Conference on Soilborne Plant Pathogens/California Nematology Workshop, UC Davis, March 21, 2011. "A new model system for root-knot nematodes on grasses and cereals"(talk). CA Nematology Workgroup Meeting, UC Davis March 22, 2011. "Biorational and biological control of plant parasitic nematodes" (talk). PARTICIPANTS: PI: J.O. Becker; Post-doctoral fellow: F. Da Silva Rocha and A. Loffredo, Department of Nematology; Senior research assistant: John Darsow; Graduate Student: Hannes Witte, Department of Nematology, UC Riverside; Collaborators: A. Ploeg, J. Smith-Becker, Department of Nematology, UC Riverside, CA; J. Borneman and J. Yang, Department of Plant Pathology and Microbiology, UC Riverside, CA; J. Karlik and J. Nunez, UCCE Kern County, Bakersfield, CA; U.K. Schuch, The School of Plant Sciences, University of Arizona; Partner Organizations: UC South Coast Research and Extension Center, Irvine, CA; UC Kearney Research and Extension Center, Reedley, CA, UC Riverside Campus, Agricultural Operations, Riverside, CA.: , University of California, Department of Plant Pathology and Microbiology, Riverside, CA, S. Benecke, Department of Statistics, UC Riverside. TARGET AUDIENCES: Our clientele include growers, pest control advisors, CDFA, USDA, industry, commodity personnel and other organizations that are affected by or interested in plant parasitic nematodes and other soilborne pathogens. My program provides information on integrated pest and disease management. This program benefits a wide range of conventional and organic growers, landscapers and home gardeners including underrepresented and minority groups. My research and extension emphasis on IPM is aimed at reducing the use of potentially hazardous pesticides which require strict safety standards during handling, application and non-entry period. These regulations are often compromised primarily because of language and/or education challenges. Safe use of pesticides and information about alternative management options are especially important for small farms, home gardens and public areas many of which are operated or managed in California by minorities and underrepresented groups. We delivered science-based information from these projects to clientele by phone, one-on-one conversations, PAPA/CAPCA presentations, PCA training sessions, UC workgroup meetings, field days, county newsletters or web bulletin boards as well as the UC IPM and Statewide CA Nematology Workgroup websites. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
We have identified only two fields among 50 sampled that expressed considerable suppressive activity against the sugar beet cyst nematode. This is in contrast to the often expressed opinion that most soils are to some degree able to reduce the activity of soilborne pathogens. Plant pathogenic nematodes appear to be less susceptible to microbial population suppression than fungal pathogens. This might indicate that soil augmentation with nematophagous microorganisms is required before the induction of nematode-suppressiveness can be expected. We isolated nematophagous fungi from a soil with suppressive activity against Meloidogyne incognita. The method of analyzing soil samples for nematode-suppressive activity might be useful for a large-scale screening. Mustard meal treatment of field plots increased yields and mitigated root-knot nematode damage similar to a dazomet treatment. Carrots grown from nematicide-coated seed had much less nematode damage than non-treated seed. We conclude that a pre-plant soil incorporation of mustard meal in combination with using abamectin-coated carrot seed is a promising strategy to minimize root-knot nematode damage in carrot. In the case of the rose replant suppression, soil analysis excluded plant parasitic nematodes as a potential cause. The transfer of the growth-suppression effect with a small amount of soil into non-suppressive soil and the elimination of the symptoms by soil fumigation strongly suggested a biological nature of the factors responsible. The research projects involved AES and AES/CE scientists as well as graduate students and post doctoral scientists in the UCR Departments of Nematology and Plant Pathology and Microbiology. The search and analysis of suppressive soils was supported by the USDA NRI grant #2007-35302-18164 and the California Sugar Beet Industry Research Committee. The carrot project was supported by the CA Carrot Research Board.

Publications

• Westphal, A., A. Pyrowolakis, R.A. Sikora, and J. O. Becker 2011. Occurrence of soil suppressiveness against Heterodera schachtii in California cropping areas. Nematropica 41:161-171.
• Loffredo, A., J. Yang, J. Borneman, and J. O. Becker. 2010. Identification of a Meloidogyne incognita-suppressive soil and its potentially causal agent. J. Nematology 42:252 (abstr.).
• Ploeg, A., O. Becker, and J. Nunez 2010. Use of cruciferous cover crops and seed coating to manage root-knot nematode in carrot. California Fresh Carrot Advisory Board Annual Report 2010. pp. 71-78
• Becker, J. O., J. Nunez, and A. Ploeg 2010. Abating root-knot nematode damage in fresh carrot production. J. Nematology 42:232-233 (abstr.).
• Becker, J. O., and J. Smith Becker 2010. A screening and optimization test for nematicidal seed coatings. J. Nematology 42:233 (abstr.).
• Da Silva Rocha, F., M. Mundo-Ocampo, J.F. Karlik, U. K. Schuch, J. A. Smith Becker, and J. O. Becker 2011. Rose replant problem apparently of biological nature. University of California Nursery and Floriculture Alliance News 15 (2):18.

Progress 01/01/10 to 12/31/10

Outputs
OUTPUTS: This project is focused on investigations into the ecology of microorganisms deleterious to soilborne plant pathogens that may be important for developing novel tools for mitigating pathogen activity. We have identified fields suppressive to Heterodera schachtii, the Sugar Beet Cyst Nematode and Meloidogyne incognita, the Southern Root-Knot Nematode. Primary contributors to the suppressiveness are the fungal hyperparasites Dactylella oviparasitica and Pochonia chlamydosporia, respectively. To further advance our understanding of the interactions between host, cyst nematode and its antagonist, we developed a gnotobiotic model system with the host/pathogen combination Arabidopsis thaliana and H. schachtii. Another project aims to reduce the use of soil fumigants against root-knot nematodes (rkn) by the use of pre-season biofumigation and a seed coating with nematicidal bacterial metabolites. We evaluated such combinations as fumigant alternatives in a highly rkn-infested carrot production field. Cover crops were grown for about 3 months before incorporation into the soil. Mustard meal was similarly incorporated. Two weeks later, carrots coated with nematicidal metabolites were seeded into subplots of the main treatment plots. Research results were presented to growers, PCAs, Master Gardeners, CDFA, USDA, industry personnel and others at 17 events: Carnival of Chemistry, ACS, CSU San Bernardino, CA, 10-24-2009. "Enlisting Microbes to Fight Plant Diseases"; Ann. CA Golf Course Superintend. Assoc., San Luis Obispo, CA, 11-2-2009. "Plant Parasitic Nematode Problems"; Plant Disease Seminar, UCCE Monterey, Salinas, CA, 11-12-2009. "The Future of Nematode Control"; UC Turfgrass & Landscape Sciences, USDA, Riverside, 1-20-2010, "Root-knot Nematodes in California Turf"; Dept Nematology, UC Riverside, 2-3-2010. "Plant Parasitic Nematodes and their Management in Turf Grasses"; CSREES Workshop 3-20-2010, Reno. "Population Dynamics of D. oviparasitica in a H. schachtii Suppressive Soil"; ANR Nematology Workgroup, UC Kearney R&E Center, CA, 3-22-2010, "Biological and biorational management of nematodes"; CA Nematology Workshop, UC Kearney R&E Center, Reedley, CA, 3-23-2010. "Hyperparasite D. oviparasitica attacking H. schachtii females"; CA Hispanic Assoc. of Professionals in Agriculture, Agr. Commissioner /W&M Department, Arcadia, CA, 4-29-2010. "Common Ornamental and Turf Diseases caused by Plant Parasitic Nematodes"; IPM Professional Landscapers, San Diego, CA, 5-27-2010. "Identification and Control of Nematodes Workshop"; OHECC, Irvine, CA, 6-10-2010. "Root-knot nematode in the Coachella Valley"; SON Annual Meeting, 07-13-2010, Boise, ID. "Optimization test for nematicidal seed coatings"; SON Annual Meeting, 07-14-2010, Boise, ID. "Abating root-knot nematode damage in fresh carrot production"; SON Annual Meeting, 07-14-2010, Boise, ID. "Suppressive soil and its potentially causal agent"; SON Industry Workshop, Boise, ID, 7-15-2010. "Bioassay for refining seedling protectants "; UCR Turf Landscape Field Day, 9-16-2010. "Nematode management". CA Hispanic Assoc. of Professionals in Agriculture, Palm Desert, CA, 9-22-2010. "Know Your Nematode Problems". PARTICIPANTS: PI: J.O. Becker, A. Ploeg, Dept. Nematology, UC Riverside; J. Borneman, Dept. Plant Pathology and Microbiology, UC Riverside, CA; Research Specialist: J. Smith Becker, Dept. Nematology, UC Riverside. Post-doctoral fellow: Angelo Loffredo, Dept Nematology, UC Riverside; Graduate student: J. Yang, University of California, Department of Plant Pathology and Microbiology, Riverside, CA, S. Benecke, Department of Statistics, UC Riverside. Collaborators: J. Nunez, UCCE Kern County, Bakersfield, CA; D.R. Jeske, Department of Statistics, UC Riverside, CA.; J. Karlik, UCCE Kern County, Bakersfield, CA. Partner Organizations: UC South Coast Research and Extension Center, Irvine, CA; UC Kearney Research and Extension Center, Reedley, CA, UC Riverside Campus, Agricultural Operations, Riverside, CA. TARGET AUDIENCES: TARGET AUDIENCES: Our clientele include growers, pest control advisors, CDFA, USDA, industry, commodity personnel and other organizations that are affected by or interested in plant parasitic nematodes and other soilborne pathogens. My program provides information on integrated pest and disease management. This program benefits a wide range of conventional and organic growers, landscapers and home gardeners including underrepresented and minority groups. My research and extension emphasis on IPM is aimed at reducing the use of potentially hazardous pesticides which require strict safety standards during handling, application and non-entry period. These regulations are often compromised primarily because of language and/or education challenges. Safe use of pesticides and information about alternative management options are especially important for small farms and home gardens many of which are operated in CA by minorities and underrepresented groups. My group delivered science-based information from these projects to clientele by phone, one-on-one conversations, PAPA/CAPCA presentations, PCA training sessions, UC workgroup meetings, field days, county newsletters or web bulletin boards as well as the UC IPM and Statewide CA Nematology Workgroup websites. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
In the gnotobiotic bioassay, D. oviparasitica reduced the average number of females developing on A. thaliana seedlings by almost 80%. On water agar, hyphae of D. oviparasitica did not exhibit distal attraction to roots or developing juveniles. However, once the fungus came in contact with a developing juvenile it grew densely, often forming an infection cushion on the surface of the nematode. Males were not susceptible to fungal infection once they had reached the J3 stage. No viable eggs developed in parasitized females. All infected females were eventually killed by the fungus. The fungus was never observed within the root. Cyst nematodes did not become infected until they broke through the root surface and were exposed to the rhizosphere. Viable eggs of H. schachtii were not susceptible to infection by the fungus in vitro, while heat- or freeze-killed eggs were rendered almost completely susceptible. Even when placed directly on mycelium of D. oviparasitica on water agar plates, the majority of non-differentiated eggs obtained from white cyst nematode females developed into juveniles. Between 5 to 10% of eggs from aseptically reared females fail to develop into juveniles. Thus, the number of non-treated, non-differentiated eggs infected by D. oviparasitica correlated to the proportion of metabolically inactive eggs. These studies provided further evidence that the nematode population reduction by the fungus is not caused through egg parasitism but parasitism of the developing juveniles and mature females. In our carrot trial, the initially low rkn populations increased under all cover crops. The biofumigation treatment reduced the rkn populations by about 50%. In contrast, soil amendment with mustard meal reduced the rkn population density close to detection level. This abated crop damage and resulted in increased yield. For all main treatments, carrots derived from abamectin-coated seed were more vigorous, had much less nematode damage and higher yields than those without the nematicidal seed coating. Fresh cruciferous plant material may not provide sufficient biofumigation efficacy to overcome rkn population increase during the crop's growth. The mustard meal warrants further investigations concerning reduced application rates. Abamectin seed coating improved carrot growth across all pre-season treatments. Soil amendment with mustard meal in combination with abamectin-coated carrot seed appears to be a sound strategy to mitigate rkn damage in carrot production. The research on microorganisms deleterious to nematodes involved AES and AES/CE scientists as well as graduate students and post doctoral scientists in the UCR Departments of Nematology and Plant Pathology and Microbiology. The H. schachtii project was supported by the USDA NRI grant #2007-35302-18164 "Understanding the interactions among the nematode, beneficial microorganisms and crop species in a Heterodera schachtii suppressive soil" (Co-PI J. Borneman). The carrot project was supported by the CA Carrot Research Board (Co-PI A. Ploeg and J. Nunez).

Publications

• Rocha, F.S., J. Smith Becker, S. Benecke, D.R. Jeske, J. Borneman, and J.O. Becker 2009. Influence of population densities of Dactylella oviparasitica and Heterodera schachtii on sugarbeet cyst nematode population suppression. J. Nematology 41:375.
• Ploeg, A., J. Nunez, and J.O. Becker 2010. Cover cropping and seed coating to mitigate root-knot nematode damage in carrot. Communications in Agricultural and Applied Biological Sciences 75:476.
• Becker, J.O. 2010. Carrot Seed Treated with Nematicides: A New Plant Protection Tool Carrot County 18 (1):8-9.
• Becker, J.O., and J.A. Smith Becker 2009. Nematology outreach in California. J. Nematology 41:308.

Progress 01/01/09 to 12/31/09

Outputs
OUTPUTS: One hundred and fifty years after the discovery of the first root-feeding nematode, sedentary endoparasitic nematodes remain the economically most important nematode pests. In our project on natural soil suppressiveness against Heterodera schachtii, we have identified the soil fungus Dactylella oviparasitica as the primary causal agents for this phenomenon in our field 9E. After a few years of no host crop in field 9E, we conducted a survey for the presence of D. oviparasitica. Field 9E was divided into 16 equal size sections and approximately 500 cc soil was collected from each part. The soil was processed with a modified Fenwick extraction method for cysts of H. schachtii. Root boxes filled with 9E field soil were set up and infested with second-stage juveniles of H. schachtii. Developing females were isolated and analyzed for D. oviparasitica. In another project we analyzed a soil that showed strong Prunus seedling suppression in a replant orchard. In the absence of obvious major pathogens, we hypothesized the presence of one or more biotic factors that caused this replant phenomenon. The results were presented to growers, PCAs, Master Gardeners, CDFA, USDA, industry, personnel and other interested parties at the following 14 outreach events. Int. Carrot Congress, Anaheim, CA. "A New Carrot Protection Tool", 1-20-2009. UCANR Sugarbeet Workgroup, UC Desert Center, Holtville, CA. "Recent Advances in Sugarbeet Cyst Nematode Research", 1-26-2009. University of Hanoi delegation, UC Riverside, CA. "Management of Plant-Parasitic Nematodes and Other Soilborne Pathogens", 2-17-2009. Visiting delegation from China, UC Riverside, "Nematodes in CA Citrus production", 3-3-2009. Nematology/Soil Fungus WS, Salinas, CA. "Combined Biological and Biorational Approach to Root-Knot Nematodes", 3-25-2009. UCCE Landscape Diagnostic Workshop, Quail Gardens, Encinitas, CA. "Nematodes in Landscape", 5-21-2009. Society of Nematologists Annual Meeting, Vermont, "Influence of population densities of Dactylella oviparasitica and Heterodera schachtii on sugarbeet cyst nematode population suppression" 7-13-2009. American Phytopathological Society, Portland, OR. Symposium: Globalization and new waves of immigration of plant pathogens. "Stealth invaders: lessons on nematode dissemination", 8-4-2009. Extension Symposium, SON Annual Meeting, Burlington, VT. "Nematology Outreach in California", 7-14-2009. Field day, UC South Coast Research and Extension Center, Irvine, CA. "Novel Developments in Crop Protection Against Phytonematodes", 8-25-2009. Ann. Turfgrass/Landscape Field Day, UC Riverside, CA. Panel member: "Ask the Expert", 9-17-2009. UC ANR Landscape WG meeting, Huntington Garden, San Marino, CA. "Replant Problems in Roses", 9-18-2009. Carnival of Chemistry, 60th Anniversary San Gorgonio Section, American Chemical Society, CSU San Bernardino, CA. "Enlisting Microbes to Fight Plant Diseases", 10-24-2009. Ann. CA Golf Course Superintendent Assoc.'s meeting, San Luis Obispo, CA. "Plant Parasitic Nematode Problems", 11-2-2009. Plant Disease Seminar 2009, UCCE Monterey County, Salinas, CA. "Review of Nematode Problems and the Future of Nematode Control", 11-12-2009. PARTICIPANTS: PI: J.O. Becker, University of California, Department of Nematology, Riverside, CA; J. Borneman, University of California, Department of Plant Pathology and Microbiology, Riverside, CA; post-doctoral fellows: A. Loffredo, University of California, Department of Nematology, Riverside, CA E. Bent, University of California, Department of Plant Pathology and Microbiology, Riverside, CA; graduate student: J. Yang, University of California, Department of Plant Pathology and Microbiology, Riverside, CA; Other collaborators: J. Smith Becker, University of California, Department of Nematology, Riverside, CA.; M. McKenry, University of California, Department of Nematology, Riverside, CA; B.B. Westerdahl,University of California, Department of Nematology, Davis, CA; A. Ploeg, University of California, Department of Nematology, Riverside, CA; A. Westphal, Julius Kuhn-Institut, Federal Research Centre for Cultivated Plants, Munster, FRG; Partner Organizations: University of California South Coast Research and Extension Center, Irvine, CA; University of California, Riverside Campus, Agricultural Operations, Riverside, CA. TARGET AUDIENCES: Target audiences for this project include growers, commodity groups, pest control advisors and other organizations that are affected by or interested in plant parasitic nematodes and other soilborne pathogens. Our program provides information on natural plant disease suppression which benefit a wide range of conventional and organic growers, landscapers and home gardeners including underrepresented and minority groups. My research and extension emphasis on alternatives to currently used pesticides is aimed at reducing the use of hazardous materials which require strict safety standards during handling and application. These regulations are often compromised due to language and/or education problems. The safe use of alternative methods to pesticides will be especially important for small farms and home gardens many of which are operated by minorities and underrepresented groups. We delivered science-based information from this project to stakeholders by phone or one-on-one conversations, workgroup presentations, PCA training sessions, field days, county newsletters and the UC IPM website. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Nematode cysts from 9E soil were analyzed for the presence of D. oviparasitica. Using a sequence-selective quantitative PCR assay, D. oviparasitica was detected in only one of the 16 locations. Apparently the lack of host plants for the sugar beet cyst nematode lead to a drop in the population density of the fungal antagonist. D. oviparasitica was also not detected in soil or purslane weed seeds (Portulaca oleracea) collected from this field. However, in the root box experiment when freshly developed H. schachtii females and cysts were isolated from roots of sugar beets grown in the suppressive 9E soil, high levels (109 copies per cyst) of D. oviparasitica were detected. Phylogenetic analysis of the rRNA intergenic transcribed spacer region identified two D. oviparasitica phylotypes. In the replant study, biocidal treatments of the soil led to considerable growth increases of Nemaguard peach seedlings. In addition, plants grown in as little as 1% of the replant soil exhibited reduced plant growth. These results suggest that the disease etiology has a biological component. Analysis of roots from plants exhibiting various levels of replant disease symptoms showed little difference in the amounts of PCR-amplified bacterial or fungal rRNA genes. However, analysis using a stramenopile-selective PCR assay showed that rRNA genes from this taxon were generally more abundant in plants with the smallest top weights. Sequence-selective quantitative PCR assays targeting four of the most abundant phylotypes showed that the oomycete Pythium ultimum and a diatom (Sellaphora spp.) and were negatively associated with plant top weights. The research on identification and testing microorganisms deleterious to nematodes involved AES and AES/CE scientists as well as graduate students and post doctoral scientists in the UCR Departments of Nematology and Plant Pathology/Microbiology. The surveys for suppressive field locations were conducted in cooperation with county-based UCCE and UCIPM advisors. The H. schachtii project was supported by the USDA NRI grant #2007-35302-18164 "Understanding the interactions among the nematode, beneficial microorganisms and crop species in a Heterodera schachtii suppressive soil" (Co-PI James Borneman). The replant project was supported in part by the California Association of Nurseries and Garden Centers and the USDA-CSREES Methyl Bromide Transitions program (Co-PI James Borneman).

Publications

• Westerdahl, B.B., A.T. Ploeg, and J.O. Becker 2009. Carrot: Nematodes. Pp. 35-37. In: UC IPM Pest Management Guidelines: Carrot, UC ANR Publication 3438, Publication URL: http://www.ipm.ucdavis.edu/PDF/PMG/pmgcarrot.pdf
• Westerdahl, B.B., and J.O. Becker 2008. Nematodes. Pp. 27-28. In: UC IPM Pest Management Guideline: Onion/Garlic, UC ANR Publication 3453. http://www.ipm.ucdavis.edu/PDF/PMG/pmgoniongarlic.pdf
• Becker, J.O., and B.B. Westerdahl 2008. Nematodes. Pp. 143-146. In: UC IPM Pest Management Guideline: Citrus, UC ANR Publication 3441, Publication URL: http://www.ipm.ucdavis.edu/PDF/PMG/pmgcitrus.pdf
• Westerdahl, B.B., A.T. Ploeg, and J.O. Becker 2008. Nematodes. Pp. 28-29. In: UC IPM Pest Management Guideline: Celery, UC ANR Publication 3439, Publication URL: http://www.ipm.ucdavis.edu/PDF/PMG/pmgcelery.pdf
• Westphal, A., J. Borneman, and J.O. Becker. 2009. Ecology of Heterodera schachtii: The soil is a dangerous place for this plant-parasite. Journal of Plant Diseases and Protection. 116:190-191.
• Bent, E., A. Loffredo, J. Yang, M.V. McKenry, J.O. Becker, and J. Borneman 2009. Investigations into peach seedling stunting caused by a replant soil. FEMS Microbiology Ecology 68: 192-200.

Progress 01/01/08 to 12/31/08

Outputs
OUTPUTS: The beet cyst nematode Heterodera schachtii is economically one of the most important plant parasitic nematodes. Although several soil fungi are known as potential antagonists of this nematode, few have ever been shown to reduce field populations below damage threshold. We focused on a field with a 25 year history of suppressiveness towards H. schachtii. Despite the presence of an infective beet cyst nematode population, frequent cropping to susceptible hosts, suitable environmental and soil physical conditions, the nematode population density has remained at a low level. Two soil fungi, Dactylella oviparasitica and Fusarium spp. were identified as the most likely causal agents for this phenomenon. Reintroduction of those fungi into fumigated soil found only D. oviparasitica able to reduce an introduced H. schachtii population to low levels. This was puzzling because frequent isolations of Fusarium spp. from beet cyst nematode eggs had suggested the participation of those fungi in the suppressiveness. Related work by Kerry and co-workers at Rothamsted, UK had demonstrated that variablility among strains of biocontrol fungi may be the cause of differences in strain efficacy. In addressing this hypothesis, we isolated dozens of strains of Fusarium spp. from parasitized eggs of H. schachtii obtained from the suppressive soil. They were initially grouped by colony appearance on solid agar media. Further genetic testing helped to select representative strains for greenhouse efficacy tests. Those strains were individually evaluated in greenhouse tests for their potential to parasitize beet cyst nematode eggs and to cause H. schachtii population suppression. Each test strain was introduced into fumigated soil. A Swiss chard seedling was transplanted into each pot that was infested with H. schachtii. After 9 weeks, the nematode population levels and egg parasitism were determined. Root-knot nematodes (Meloidogyne spp.) are economically even more important in California and world-wide than cyst nematodes. The species in CA have a very wide host range which makes crop management schemes difficult. Although certain soil fungi and bacteria are able to parasitize these nematodes, soil suppressiveness against Meloidogyne spp. has rarely been reported. Such events are not as abundant as with cyst nematodes because root-knot females are typically less exposed to the rhizosphere than some of the cyst nematodes. Also, even if population suppression occurs, it is difficult to detect as the main damage symptom is initiated before female or egg parasitism can take place. Surveys based entirely on root damage are therefore less suitable to detect root-knot nematode suppressive situations. We designed a screening system that included two different hosts, a dwarf tomato and wheat. We collected soil from several California locations that have been known to be inhospitable to various plant parasitic nematodes although not necessarily for Meloidogyne spp. These were assayed in greenhouse tests for suppressiveness to M. incognita. The results of these projects were presented to growers, PCAs, Master Gardeners and other interested parties at 12 outreach events. PARTICIPANTS: PI: J.O. Becker, University of California, Department of Nematology, Riverside, CA; Co-PI: J. Borneman, University of California, Department of Plant Pathology and Microbiology, Riverside, CA; post-doctoral fellows: X. Gao, University of California, Department of Nematology, Riverside, CA; A. Loffredo, University of California, Department of Nematology, Riverside, CA E. Bent, University of California, Department of Plant Pathology and Microbiology, Riverside, CA; graduate student: B. Yin, University of California, Department of Plant Pathology and Microbiology, Riverside, CA; Partner Organizations: University of California South Coast Research and Extension Center, Irvine, CA; University of California, Riverside Campus, Agricultural Operations, Riverside, CA. Collaborators: M. McKenry, University of California, Department of Nematology, Riverside, CA. TRAINING AND OUTREACH SESSIONS: Sugarbeet Workgroup meeting, UC Desert Research and Extension Center, Holtville, CA, January 16, 2008. "Sugar beet cyst nematode research, new developments"; Carrot Meeting, Bakersfield, March 11, 2008. Nematode Panel Discussion Member: "Fumigation, Alternative Materials and Resistance"; Floriculture and Nursery Workgroup meeting, UC Riverside, CA, March 20, 2008. "Of Worms and Trees"; Nematology Workgroup meeting, UC Davis, March 24, 2008. "Research on disease- and growth-suppressive organisms"; 40th CA Nematology Workshop, UC Davis, March 25, 2008. "Hyperparasite Dactylella oviparasitica"; Soil Fungus Conference, St. Paula, March 26-28, 2008. "Dactylella oviparasitica: responsible for nematode population suppression"; University of California Cooperative Extension/Port of San Diego: IPM for Landscapers training, San Diego, June 4, 2008. "What's new in nematodes"; Northern Regional Training for Master Gardeners, University of California,Davis Campus, July 17/18, 2008. "Introduction to Plant Parasitic Nematodes"; Expanding Horizons, UC Riverside Extension Center, July 23, 2008. "When Plants Get Sick"; UCR Turfgrass & Landscape Research Field Day. September 4, 2008, UC Riverside. "You think you have nematodes Proper sampling, diagnosis, and action steps". TARGET AUDIENCES: Target audiences for this project include growers, commodity groups, pest control advisors and other organizations that are affected by or interested in plant parasitic nematodes and other soilborne pathogens. Our program provides information on natural plant disease suppression which benefit a wide range of conventional and organic growers, landscapers and home gardeners including underrepresented and minority groups. My research and extension emphasis on alternatives to currently used pesticides is aimed at reducing the use of hazardous materials which require strict safety standards during handling and application. These regulations are often compromised due to language and/or education problems. The safe use of alternative methods to pesticides will be especially important for small farms and home gardens many of which are operated by minorities and underrepresented groups. We delivered science-based information from this project to stakeholders by phone or one-on-one conversations, workgroup presentations, PCA training sessions, field days, county newsletters and the UC IPM website. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
The isolated H. schachtii egg parasites differed substantially in colony appearance and metabolite production on solid culture media. We grouped them by their colony appearance on potato dextrose agar and subjected representative isolates from each group to phylogenic analysis. The seven selected Fusarium strains parasitized H. schachtii eggs, but at considerably different levels. While one strain parasitized less than 10% of the eggs, the most aggressive strain was found in approximately 35% of the eggs. This degree of parasitism was not significantly different from the one observed in the suppressive soil. However, in contrast to the originally suppressive soil, in none of the Fusarium-infested soils was the population of H. schachtii significantly reduced after two nematode generations. Greenhouse trials with two susceptible hosts of Meloidogyne incognita, a dwarf tomato and wheat, led to the identification of a soil in which the root-knot nematode population was reduced 5- to 16-fold compared to identical but pasteurized soil two months after infestation with 280 M. incognita J2/100 cm3 soil. The suppressive soil was subjected to various temperature, fumigation and dilution treatments, planted with tomato, and infested with 1,000 eggs of M. incognita/100 cm3 soil. Eight weeks after nematode infestation, distinct differences in nematode population densities were observed among the soil treatments, suggesting a biological component of the suppressiveness. A fungal rRNA gene analysis (OFRG) performed on M. incognita egg masses collected at the end of the greenhouse experiments identified 11 fungal phylotypes, several of which exhibited associations with one or more of the nematode population density measurements (egg masses, eggs or J2). The phylotype containing rRNA genes with high sequence identity to the fungus Pochonia chlamydosporia exhibited the strongest negative associations. The negative correlation between the densities of the P. chlamydosporia genes and the nematodes was corroborated by an analysis using a P. chlamydosporia-selective qPCR assay. The research on identification and testing nematode-deleterious microorganisms involved AES and AES/CE scientists as well as graduate students and post doctoral scientists in the UCR Nematology and Plant Pathology Departments. The surveys for suppressive field locations were conducted in cooperation with county-based UCCE and UCIPM advisors. The H. schachtii project was supported by the USDA NRI grant "Understanding the interactions among the nematode, beneficial microorganisms and crop species in a Heterodera schachtii suppressive soil" (Co-PI James Borneman). The root-knot nematode project was supported by the USDA/CREES grant "Identification of Microorganisms Involved in Meloidogyne incognita Suppressiveness" (Co-PI James Borneman).

Publications

• Gao, X., Yin, B., Borneman, J. and Becker, J.O. 2008. Assessment of parasitic activity of Fusarium strains obtained from a Heterodera schachtii-suppressive soil. Journal of Nematology 40(1):1-6.
• Bent, E., Loffredo, A., McKenry, M.V., Becker, J.O. and Borneman, J. 2008. Detection and investigation of soil biological activity against Meloidogyne incognita. Journal of Nematology 40(2):109-118.
• Loffredo, A., Bent, E., McKenry, M.V., Borneman, J. and J.O. Becker 2007. Understanding a root-knot nematode suppressive soil. J. Nematology 39:86.

Progress 01/01/07 to 12/31/07

Outputs
The long-term goal of this research is to develop more effective and sustainable management strategies for soilborne pathogens, including plant parasitic nematodes. Defining the key interactions responsible for soil suppressiveness should create the foundational knowledge from which these new management strategies can be developed. We identified the fungal hyperparasite Dactylella oviparasitica as the primary microorganism causing a stable population suppression of the beet cyst nematode at a field site near UC Riverside. Reintroduction of the fungus into conducive, H. schachtii-infested soils caused a nematode-population decline and consequent suppression similar to the original field site. An A. thaliana model system was developed for the study of the mode of action of the biocontrol agent Dactylella oviparasitica against the beet cyst nematode Heterodera schachtii. Four weeks after nematode infestation, A. thaliana (type Landsberg erecta) grown in sandy soil in the presence D. oviparasitica had a 70% reduction in the number of mature cysts compared to control plants. A second system enabled the direct observation of the interaction of the fungus with developing juveniles in agar plate cultures. At 22 C, the majority of developing juveniles broke through the root epidermis 17 days after infestation with H. schachtii. Hyphae of D. oviparasitica were not attracted to nematode-free roots but rapidly colonized the juveniles as they began to emerge from the root surface. Parasitism of 4th stage juveniles terminated further development into adult males and females. These observations suggest that parasitism of developing juveniles and young females may be the primary mode of action in the population suppression of H. schachtii.

Impacts
The identification of the causal agent for the population decline and suppression of the sugarbeet cyst nematode is the first step in developing a novel management tool for this pathogen. Our methodology for investigating suppressive soils is considered a blueprint for similar tasks. The results and conclusions of this project were extended in 15 outreach presentations to various audiences.

Publications

• Borneman J, J.O. Becker, E. Bent, B. Lanoil, B.B. McSpadden Gardener, R. Olatinwo, L. Presley, A.J. Scupham, L. Valinsky, B. Yin 2007. Identifying microorganisms involved in specific in situ functions: experimental design considerations for rRNA gene-based population studies and sequence-selective PCR assays, Page 748-757 in: Christon J. Hurst (ed.) Manual for Environmental Microbiology (3rd ed). ASM Press, Washington D.C., ISBN: 9781555813796.
• Karlik, J.F., J.O. Becker, C.H. Haas, and U.K. Schuch 2007. Delivery of gases via drip irrigation tubing: An exploratory study. Acta Horticulturae 751:69-76
• Borneman, J., and J.O. Becker 2007. Identifying Microorganisms Involved in Specific Pathogen Suppression in Soil. Annual Review of Phytopathology 45: 153-72.
• Becker, A.-G., and J.O. Becker 2007. Bioassay for root-knot nematode-inhibiting activity in soil. Proceed. 2007 Annual International Research Conference on Methyl Bromide Alternatives and Emissions Reductions, San Diego, 113-1.
• Smith-Becker, J., J. Borneman, and J.O. Becker 2007. Trixenic cultures to study population suppression of the beet cyst nematode in Arabidopsis thaliana by Dactylella oviparasitica. J. Nematology 39: 86.
• Borneman, J. and J.O. Becker 2007. Examining nematode-suppressive soils. Phytopathology 97: S154.

Progress 01/01/06 to 12/31/06

Outputs
Seed coating with abamectin, a mixture of nematicidal metabolites of Streptomyces avermitilis were shown to protect seedlings against root-knot nematodes in several vegetable crops and cotton. Mitigation of nematode-caused crop damage resulted in significant yield increases despite the relatively short protection period. The seed coating also reduced nematode-promoted fungal diseases. In combination with fungal biological control agents nematode-caused plant diseases and crop damage were further reduced than with either approach alone.

Impacts
Biorational approaches against root-knot nematodes are potential alternatives to current practice by utilizing microbial agents, their metabolites or a combination of both. Abamectin seed coating in cotton has been used in its first season on approximately 2 million acres.

Publications

• Becker, J.O., H.V. Morton, J. Smith Becker, and D. Hofer 2006. Early protection against root-knot nematodes through nematicidal seed coating provides season-long benefits for cucumbers. Proceedings Cucurbitaceae 2006, Asheville, NC
• Smith Becker, J., and J.O. Becker 2005. Seedling protection of Pima cotton against nemaode-induced Fusarium wilt by a nematicidal seed coating. J. Nematology 37:396. (abstract)
• Karlik, J.F., J.O. Becker, C.H. Haas and U.K. Schuch 2005. Delivery of gases via drip irrigation tubing: an exploratory study. Fourth International Symposium Rose Research and Cultivation Abstract Booklet, 3 (abstract)
• Becker, J.O., and J. Becker Smith 2006. Nematicidal seed coating reduces root-knot nematode-enhanced Rhizoctonia damping-off in cotton. J. Nematology 38: 261. (abstract)
• Becker, J.O, M.A. Braim, J. King 2006. Mitigation of root health problems in Saudi Arabian wheat production. J. Nematology 38: 260-261 (abstract)
• Becker, J.O. Seed-delivered disease protection. 232nd ACS National Meeting, San Francisco, CA, September 10-14, 2006. (abstract)
• Hofer, D., H.V. Morton, D. Long, and J.O. Becker 2005. Improved plant protection by a unique seed delivered nematicide. British Crop Protection Congress - Crop Science & Technology 3B-4: 213-222.
• Chen, X., S. Mueller, and J.O. Becker 2006. Improved plant protection against root-knot nematodes by combining biorational approaches. Proceed. 2006 Annual International Research Conference on Methyl Bromide Alternatives and Emissions Reductions, Orlando, 50-1 - 50-2.
• Yan, C., D. Merhaut, and O. Becker 2005. Hydroponic Sunflower Production as Influenced by Cultivar, Nitrogen Fertilization, and Root-knot Nematode Infestation. American Society for Horticultural Science (abstract)
• Becker, J.O. 2005. Seed coating with a natural nematicide: a newfangled technology for plant protection. Journal of Nematology 37:357. (abstract)

Progress 01/01/05 to 12/31/05

Outputs
A modified semi-selective medium was developed to isolate and quantify the nematophagous fungus Pochonia chlamydosporia. Seed coatings with nematicidal metabolites of Streptomyces avermitilis were shown to protect seedlings against root-knot nematodes in a number of vegetable crops and cotton. The reduction of the nematode-caused damage was sufficient to result in significant yield increases. Persistence of the nematicide fosthiazate was found to be similar to other op-nematicides. Combinations of soil fumigants resulted in increased efficacies against various agricultural pests.

Impacts
Biorational plant protection against root-knot nematodes by utilizing microbial agents or their metabolites is a potential alternative to current soil application of non-fumigant nematicides. Seed coating with bacterial metabolites that exhibit nematicidal activity appears to be an economically and ecologically sound approach.

Publications

• Becker, J.O., and D. Hofer 2004. Efficacy comparison between seed-coated and soil-applied nematicides in root-knot nematode-infested cucumber fields. Phytopathology 94:S7 (abstract).
• Becker, J.O. 2004. Nematode control vs. plant protection. Journal of Nematology 36:306 (abstract).
• Smith Becker, J., and J.O. Becker 2004. Early protection of cotton seedlings by abamectin seed coating against root-knot nematodes. Journal of Nematology 36:346 (abstract).
• Fischer, R., and J.O. Becker 2004. Comparison of Fenwick can and Schuiling centrifuge extraction of cysts of the sugar beet nematode Heterodera schachtii. Journal of Nematology 36:317 (abstract).
• Payan, L. A., and J.O. Becker 2004. Biorational seedling protection against plant-parasitic nematodes. Nematropica 34:122 (abstract).
• Qin, S., J. Gan, W. Liu and J.O. Becker 2004. Degradation and adsorption of fosthiazate in soil. Journal of Agricultural and Food Chemistry 52:6239 - 6242.
• Hutchinson, C.M., M.E. McGiffen Jr., J.J. Sims, and J.O. Becker. 2004. Fumigant combinations for Cyperus esculentum L control. Pest Management Science 60:369-374.
• Chen, X., Jiang, Y., and J.O. Becker 2005. Modification of a semi-selective medium for isolation and quantification of the nematophagous fungus Pochonia chlamydosporia. Journal of Shanghai Jiiaotong University (Science) Vol. E-10: 172-175.
• Chen, X., and J.O. Becker 2004. Dactylella oviparasitica as biocontrol agent for Meloidogyne incognita in tomato. Proceedings 15th International Plant Protection Congress, Beijing, China May 11-16, 2004, p. 158 (abstract).

Progress 01/01/04 to 12/31/04

Outputs
Biorational approaches in plant protection promise to reduce pesticide applications without compromising crop production efficacy or quality. Induction of plant defense mechanisms by acibenzolar-S-methyl was investigated in cantaloupe. Both Colletotrichum lagenarium and cucumber mosaic virus development were significantly reduced. The development of a seed coat based on the nematicidal metabolites of Streptomyces avermitilis is another example of a biorational strategy in plant protection. This treatment was shown to protect seedlings against various plant-parasitic nematodes in a number of vegetable crops and cotton. Although the protection period was relatively short, the mitigation of the early attack by nematodes was sufficient to result in yield increases similar to those obtained with soil-applied nematicides.

Impacts
Seed coating with a microbial-derived metabolite has the potential to reduce nematicide application rates in short-season crops by at least 100fold. Sustainable management of B. longicaudatus will benefit from information about its ecology and interaction with its hyperparasites. Pasteuria usgae is considered a major component of sting nematode population suppression at a Florida location. We have described and identified this new species that might help in suppressing the California population of B. longicaudatus.

Publications

• Smith-Becker, J., N. Keen, and J.O. Becker 2003. Acibenzolar-S-methyl induces resistance to Colletotrichum lagenarium and cucumber mosaic virus in cantaloupe. Crop Protection 22:769-774.
• Karlik, J.F., J.O. Becker, H.B. Pemberton, and U.K. Schuch 2003. Field rose production. Pp. 580-587. In: Encyclopedia of Rose Science (eds. A. Roberts, T. Debener, and S. Gudin), Academic Press, NY.
• Becker, J.O., S. Muller, X. Chen, and D. Hofer 2003. Utilization of abamectin seed coating in vegetable transplant production systems. Journal of Nematology 35:324.
• Becker, J.O., B. Slaats and D. Hofer 2004. Cucumber seed coating with abamectin guards against early root damage by root-knot nematodes. Phytopathology 94:S149.

Progress 01/01/03 to 12/31/03

Outputs
Nematode population management continues to be dominated by chemical population suppression. Our approach is a) to reduce pesticide applications without compromising crop production efficacy or quality and b) investigate biological population suppression that is key to sustainable nematode management systems. The development of a new biorational seed coating to protect seedlings against plant-parasitic nematodes appears to be a significant advancement in reducing nematicide applications to short-season crops. The sting nematode Belonolaimus longicaudatus, a native to the Southeastern part of the US, is established in several golf courses in the Coachella Valley, CA. Nemacur, the only nematicide registered for California golf courses, will be withdrawn by 2007. Thermal time requirements for the development of this nematode confirmed previously suggested seasonal population fluctuations. Natural population control of the sting nematodes has been reported in Florida. The suppression was attributed to a mycelial, endospore-forming bacterial microparasite of the species Pasteuria. The occurrence of nematode-suppressive soils is still rarely investigated. In three of 12 soils obtained from agricultural fields in California, population density development of Meloidogyne incognita under susceptible tomato was significantly suppressed when compared to identical but fumigated, M. incognita-reinfested soils.

Impacts
Seed coating with a microbial-derived metabolite has the potential to reduce nematicide application rates in short-season crops by at least 100fold. Sustainable management of B. longicaudatus will benefit from information about its ecology and interaction with its hyperparasites. Pasteuria usgae is considered a major component of sting nematode population suppression at a Florida location. We have described and identified this new species that might help in suppressing the California population of B. longicaudatus.

Publications

• Pyrowolakis, A., Westphal, A., Sikora, R.A., and Becker, J.O. 2002. Identification of root-knot nematode suppressive soils. Applied Soil Ecology 19:51-56.
• Giblin-Davis, R. M., Williams, D.S., Bekal, S., Dickson, D.W., Brito, J.A., Becker, J.O., and Preston, J.F. 2003. 'Candidatus Pasteuria usgae' sp. nov., an obligate endoparasite of the phytoparasitic nematode Belonolaimus longicaudatus. International Journal of Systematic and Evolutionary Microbiology 53:197-200.
• Luo, D., Smith-Becker, J., and Becker, J.O. 2003. Thermal time requirements for embryogenesis of the sting nematode. Phytopathology 93:S128. (abstract)
• Becker, J.O., Morton, H.V., and Hofer, D. 2003. Seedling protection against plant parasitic nematodes by abamectin seed dressing. 8th International Congress of Plant Pathology Vol. 2: 251. (abstract)

Progress 01/01/02 to 12/31/02

Outputs
The sting nematode Belonolaimus longicaudatus has received surprisingly little attention concerning its biology and ecology. Native to the Southeastern part of the US, this nematode species is established in several golf courses in the Coachella Valley, CA. Fenamiphos is currently the only nematicide registered for California golf courses and it will be withdrawn by 2007. Natural population control of the nematodes has not been observed in the infested California golf courses but has been reported in Florida. The suppression was attributed by R.M. Giblin-Davis to a previously undescribed Pasteuria strain (S-1). Pasteuria spp. are mycelial, endospore-forming bacterial microparasites of plant-parasitic nematodes. Previously described species of Pasteuria were distinguished based upon discontinuities in morphometrics, ultrastructure of mature endospores, and host attachment specificity. The ultrastructure of the mature endospore of S-1 is distinctive when compared with endospores of the named species of Pasteuria. S-1 attached and parasitized all tested populations of B. longicaudatus but not various other ecto- or endoparasitic nematodes. In another project, repetitive applications of a pseudomonad biocontrol agent proved useful in establishing and maintaining a high population density in the root zone of citrus.

Impacts
Successful management of B. longicaudatus will rely on information about its ecology and interaction with potential antagonists. The native antagonists of the sting nematode were left behind when it was introduced to California. Pasteuria S-1 is considered a major component of sting nematode population suppression at a Florida location. Our research has identified S-1 as a possible new species that might help in suppressing the California population of B. longicaudatus. Repetitive application technology has shown the potential to maintain a population of beneficial bacteria in the rhizosphere of a perennial.

Publications

• Giblin-Davis, R.M., D.S. Williams, W.P. Wergin, D.W. Dickson, T.E. Hewlett, S. Bekal, and J.O. Becker 2001. Ultrastructure and Development of Pasteuria sp. (S-1 strain), an Obligate Endoparasite of Belonolaimus longicaudatus (Nemata: Tylenchida). Journal of Nematology 33:227-238.
• Steddom, K., O. Becker, and J.A. Menge, 2002. Repetitive applications of the biocontrol agent, Pseudomonas putida 06909-rif/nal, and effects on populations of Phytophthora parasitica in citrus orchards. Phytopathology 92:850-856.
• Becker, J.O. 2001.Hurdles for integrated nematode pest management. Phytopathology 91:S174.

Progress 01/01/01 to 12/31/01

Outputs
Many details of the biology and the ecology of the sting nematode are unknown although this pest was already described in the late 1940s. Native to the Southeastern part of the US, this nematode species is an A-rated pest in CA. Since we have discovered an infestation of Belonolaimus longicaudatus in several golf courses in the Coachella Valley, CA, we have focused on some of these basic biology/ecology issues. Members of the genus Pasteuria are obligate, mycelial, endospore-forming bacterial microparasites of plant-parasitic nematodes. Some strains have been described as promising candidates for biological control of plant-parasitic nematodes. Pasteuria strain S-1, originally isolated in Florida by R.M. Giblin-Davis, was found attached to several strains of B. longicaudatus from different geographical locations within the United States including the ones from California. However, they did not adhere to any other tested nematode species. DNA sequence analysis showed that the S-1 16S rRNA had 96% or less similarity to the 16S rRNA genes from all previously reported Pasteuria species. Diverse phylogenetic methods all provided support for an association of Pasteuria strain S-1, Pasteuria strain NA parasitic to H. glycines, and P. penetrans strain Pp to the exclusion of P. ramosa.

Impacts
Integrated pest management of the sting nematode will rely in the long run on information about its ecology and interaction with natural enemies. As with many other invasive pests, many natural antagonists of the sting nematode were left behind when it was introduced to California. Our results has indicated that Pasteuria S-1 is considerably different from previously described Pasteuria species and might be a key player in suppressing the pest population.

Publications

• Bekal, S., Borneman, J.,Springer, M.S., Giblin-Davis, R.M. and Becker, J.O. 2001. Phenotypic and molecular analysis of a Pasteuria strain parasitic to the sting nematode. Journal of Nematology 33:110-115.

Progress 01/02/00 to 12/31/00

Outputs
Soil nematodes are components of a diverse microcosm with innumerable interactions among the soil biota. Even the basic details of biology and ecology of many nematode species are often unknown, let alone their behavior in the presence of antagonists. This true for the economically important sting nematode, Belonolaimus longicaudatus, which was found in several golf courses in the Coachella Valley. We monitored the population dynamics of this pest for two years and examined its host range and pathogenicity. Approximately 80% of the plants tested were classified as good hosts while only okra, watermelon and tobacco were non-hosts. Soil temperature and fluctuation of nematode densities were significantly correlated at three locations. Nematode distribution was greatest in the top 15-cm of soil except during the hottest summer months when the population was higher at 15 to 30 cm. Population density peaked in October, with 1,000 nematodes/100 cc soil, but declined rapidly with the lowest population density in December with approximately 50 nematodes/100 cc soil. We investigated DNA polymorphism within eleven populations of B. longicaudatus using ITSs and RAPD analysis. Our results showed similarity of the restriction patterns of the ITSs for all the nematode populations. RAPD patterns using 12 different decamers showed a high level of variation between the different geographic populations of the sting nematode. Another study focused on the ability of the biocontrol organisms Pasteuria penetrans to survive desiccation and remain infective after long-term storage. A soil containing spores of P. penetrans was stored in a closed can at room temperatures for 21 years. In moistened soil the spores readily attached to the cuticle of root-knot nematodes. In infested nematodes, the life cycle of the bacterial parasite was completed within eight weeks and resulted in endospore-filled nematode females.

Impacts
Any rational IPM program to manage the sting nematode will rely on information about its population dynamics and host range. This study has indicated two critical times during the year when control strategies will be most effective and beneficial. The RAPD study provided evidence that it might be possible to determine the source of the original sting nematode infestation. The survival of P. penetrans for more than 2 decades in dry soil underscores its potential as a biocontrol agent.

Publications

• Bekal, S., and J.O. Becker. 2000. Population dynamics of the sting nematode in California turfgrass. Plant Disease 84:1081-1084.
• Bekal, S., and J.O. Becker. 2000. Host Range and Pathogenicity of a California Sting Nematode Population. HortScience 35:1276-1278.
• Bekal, S., R. Mankau, and J.O. Becker 2000. Pasteuria penetrans: an infective parasite on root-knot nematodes after twenty-one years in dry soil. Phytopathology 90:S117 (abstract).
• Bekal, S., I. Kaloshian, and J. O. Becker 2000. Polymorphism within sympatric and allopatric isolates of Belonolaimus longicaudatus. Journal of Nematology (abstr., in press).

Progress 01/01/99 to 12/31/99

Outputs
Plant parasitic nematodes in soil and especially in the rhizosphere are part of a diverse microcosm with countless interactions among the soil biota. Certain stages in the life cycle of nematode pests provide potential targets for their disruption by microorganisms. Critical stages are for example the development of nematode eggs and first-stage juveniles, hatching, juvenile movement through the soil, attraction to roots, recognition of host/non-host tissue and feeding sites, attraction to opposite gender, and penetration of root tissues. However, nematodes usually dwell in an environment which is does not lend itself to easy observations. We cultured the sting nematode, Belonolaimus longicaudatus on excised corn roots and observed its complete life cycle. Behavioral studies indicated sex attractants guide males to females. Mating is required for reproduction. Thus, the phase of attraction might be an interesting target microbial interference. Furthermore, we were able to gnotobiotically culture a strain of Pasteuria in our sting nematode system.

Impacts
Our research lead to the first complete description of the life cycle of the sting nematode. Any rational IPM program to manage sting nematode infestations will rely on this information. The gnotobiotic culture of Pasteuria will be the basis for ecological and genetic studies designed to advance biological control of this nematodes.

Publications

• Huang, X. and J.O. Becker 1999. Life cycle and mating behavior of Belonolaimus longicaudatus in gnotobiotic culture. Journal of Nematology 31:70-74.
• Bekal, S., R.M. Giblin-Davis and J.O. Becker 1999. Gnotobiotic culture of Pasteuria sp. on Belonolaimus longicaudatus. Journal of Nematology 31:522.
• Neipp, Paul, and J.O. Becker 1999. Evaluation of biocontrol activity of rhizobacteria from Beta vulgaris against Heterodera schachtii . Journal of Nematology 31:54-61.

Progress 01/01/98 to 12/01/98

Outputs
Certain development stages of most plant parasitic nematodes commonly are exposed to countless interactions among roots of host/non-host plants, soil biota, and the physical and chemical environment of the rhizosphere. Potential targets for disruption by microorganisms are the development of nematode eggs and first-stage juveniles, hatching, juvenile movement through the soil, attraction to roots, recognition of host/non-host tissue and feeding sites, attraction to opposite gender, and penetration of root tissues. One hundred fifty rhizobacteria isolated from roots of Swiss-chard grown in a soil suppressive to the sugar beet cyst nematode, HETERODERA SCHACHTII, were tested for their influence on the nematode's ability to hatch and to infect roots. Two screening systems were used that focused on the ability of bacteria to inhibit either nematode hatching or root infection. Nine percent of all strains significantly reduced second-stage juvenile infection of mustard roots raised in soil-less growth pouches. Eighteen strains from four genera (BACILLUS, PSEUDOMONAS, VARIOVORAX, and ARTHROBACTER) were selected for greenhouse trials. In the greenhouse trials, two strains of BACILLUS MEGATERIUM reduced nematode infection of sugar beet when eggs were used as inoculum. Seven bacterial strains reduced nematode infection of sugar beet when plants were inoculated with second-stage juveniles. Most of the effective strains were BACILLUS spp., primarily B. MEGATERIUM. Colonization of sugar beet roots by two B. MEGATERIUM strains was found to be stable over 30 days in the greenhouse.

Impacts
(N/A)

Publications

• NEIPP, P., and J.O. BECKER 1998. Evaluation of biocontrol activity and colonization potential of rhizobacteria effective against HETERODERA SCHACHTII. Journal of Nematology 30 (abstr., in press).

Progress 01/01/97 to 12/01/97

Outputs
Plant health-promoting rhizobacteria have been identified by many research groups as a natural resource to achieve plant disease suppression without the health and environmental problems related to pesticide use. We developed a rapid screening system to identify plant-beneficial rhizobacteria useful in protecting nursery seedlings against damping-off caused by RHIZOCTONIA SOLANI. Approximately 0.5% of 7000 bacterial strains tested reduced damping-off significantly in greenhouse trials. Fifteen bacterial strains controlled Rhizoctonia damping-off by 30-60% compared to the non-treated control. In another research project 5% of 150 rhizobacteria isolated from a nematode suppressive soil inhibited in vitro hatching of HETERODERA SCHACHTII entirely. Nine percent of all strains significantly reduced infection of mustard roots by juveniles of H. SCHACHTII. Most of the active strains were identified as BACILLUS species. Furthermore, we have demonstrated that methyl iodide is a valuable research tool for manipulating and studying biotic activity in soil. Its efficacy against a wide range of plant parasitic nematodes and plant pathogens is equal or better than methyl bromide. Due to its physical characteristics it is easier and safer to use than methyl bromide.

Impacts
(N/A)

Publications

• BECKER, J.O. and SCHUCH, U.K. 1997. Rapid screening of rhizobacteria for suppression of rhizoctonia damping-off. HortScience 32:468.
• NEIPP, P. and BECKER, J.O. 1997. Effects of rhizobacteria on hatching and root invasion of the sugarbeet cyst nematode HETERODERA SCHACHTII. J. Nematology 29: In Press.
• BECKER, J.O., OHR, H.D., McGIFFEN,JR., M. and SIMS, J.J. 1997. Hot gas application of methyl bromide and methyl iodide for soil fumigation field trials. Proceedings of 1997 Annual International Research Conference on Methyl Bromide Altern.
• HUTCHINSON, C.M., BECKER, J.O., McGIFFEN, JR., M., OHR, H.D. and SIMS, J.J. 1997. Efficacy of methyl iodide against nematodes and plant pathogens. Proceedings of 1997 Annual International Research Conference on Methyl Bromide Alternatives.
• BECKER, J.O., McGIFFEN, JR., M.E., OHR, H.D. and SIMS, J.J. 1997. Achievable yield in a commercial fresh carrot production field in California. Proceedings of 1997 Annual International Research Conference on Methyl Bromide Alternatives.
• BECKER, J.O. 1997. Methyl iodide shows promise as soil fumigant. Carrot Country 5(2):25-26.

Progress 01/01/96 to 12/30/96

Outputs
The objective of this program is to identify and characterize plant-microbe interactions that provide suppression to disease caused by plant parasitic nematodes and soilborne plant pathogens. We are investigating several nematode-suppressive soils. Fumigation was used as a research tool to obtain information about the yield potential at a given field site. At a field site in Imperial County, pre-plant soil solarization and soil fumigation with methyl bromide/chloropicrin had only a rather small effect on cyst nematode population found after the first season when compared to the non-treated control. The decrease in the number of eggs/g soil and number of eggs/cyst in the control plots at the end of the second season indicated the presence of antagonistic organisms which naturally suppressed the cyst nematode population. Both solarization and fumigation apparently reduced the suppressive effect which resulted in the increase of the cyst nematode population. Methyl iodide proved to be a more convenient and safer research tool than methyl bromide. We have identified methyl iodide as a potential soil fumigant which is at equal molar concentrations as effective as methyl bromide against a wide range of soil-borne pests and pathogens. Its physical characteristics, namely its photolability and relative high boiling point, suggest an insignificant ozone-depletion potential and allows to handle the compound at room temperature in its liquid form.

Impacts
(N/A)

Publications

• BECKER, J. O., WRONA, A.F. and LEWELLEN, R.T. 1996. Effect of solarization and soil fumigation on sugar beet cyst nematode population. Biological and Cultural Tests for Control of Plant Diseases 11: 19.
• OHR, H.D., SIMS, J.J., GRECH, N.M., BECKER, J.O. and MCGIFFEN M. E., JR. 1996. Methyl iodide, an ozone-safe alternative for methyl bromide as a soil fumigant. Plant Disease 80: 731-735.
• SIMS, J.J., OHR, H.D., GRECH, N.M., BECKER, J. O. and MCGIFFEN, M. E., JR. 1996. Methyl Iodide: a single chemical replacement for methyl bromide. Methyl bromide alternatives Vol.2 (2): 9.
• BECKER, J.O., OHR, H.D., GRECH, N.M., MCGIFFEN, M. E., JR. and SIMS, J.J. 1996. Soil fumigation with methyl iodide. Mitt. Biol. Bundesanstalt 321: 596.
• BECKER, J.O., OHR, H.D., MCGIFFEN, M. E., JR., and SIMS, J.J. 1996. Comparison ofefficacy between methyl bromide and methyl iodide against plant parasitic nematodes. Proceed. 1996 Annual International Research Conference on Methyl Bromide.

Progress 01/01/95 to 12/30/95

Outputs
This research program is aimed at economic and ecological sound IPM systems for managing plant parasitic nematodes and soil-borne diseases. The expected loss of methyl bromide as a soil fumigant by the year 2001 demands the development of short-term chemical alternatives as well as long-term plant and nematode management strategies. We have identified methyl iodide as a potential soil fumigant which is at equal molar concentrations at least as effective as methyl bromide against a wide range of soil-borne pests and pathogens. Other microorganisms such as fluorescent pseudomonas may actually increase a few days after the treatment. It is believed that methyl iodide has an insignificant ozone depletion potential due to its photolability. Its physical characteristics and biological activity makes this compound a prime candidate for replacing methyl bromide. In the inland deserts of Southern California we have shown that solarization can be an effective non-chemical alternative to soil fumigation in short season row crops. In turf, a new application system for soil pesticides was developed which was designed to specifically target nematode-infested areas. Sting nematode (BELONOLAIMUS LONGICAUDATUS) can be controlled for several months by low rates of metham sodium in established turf when applied with the new device. Disease suppression of RHIZOCTONIA seedling damping-off with beneficial root-colonizing bacteria was mainly due to the in situ production of pyrrolnitrin.

Impacts
(N/A)

Publications

• MCGIFFEN, M.E., JR., J.O. BECKER, H.D. OHR, J.J. SIMS, and N.M. GRECH. 1995. Methyl iodide: an effective replacement for methyl bromide for weed control.
• Proceed. 1995 Annual International Research Conference on Methyl Bromide Alternatives.
• BECKER, J.O. 1995. Spot-treatment of turfgrass with a soil fumigant to suppress sting nematodes. Fungicide and Nematicide Tests 50: 211.
• OHR, H.D., J.J. SIMS, N.M. GRECH, J.O. BECKER, and M.E. MCGIFFEN. 1995. Methyl Iodide: an effective replacement for methyl bromide for preplant fumigation of soil fungi. Proceed. 1995 Annual International Research Conference on Methyl Brom.
• SIMS, J.J., N.M. GRECH, J. O. BECKER, M. MCGIFFEN, JR., and H.D. OHR. 1995. Methyl Iodide: A potential alternative to methyl bromide. Proceed. 1995 Annual International Research Conference on Methyl Bromide Alternatives and Emissions Reduc.
• BECKER, J.O., N.M. GRECH, H.D. OHR, M. MCGIFFEN, and J.J. SIMS. 1995. Efficacy of methyl iodide against root-knot nematodes in bucket and field trials.
• Proceed. 1995 Annual International Research Conference on Methyl Bromide Alternatives.

Progress 01/01/94 to 12/30/94

Outputs
The objective of this research program is to develop economic and ecological sound IPM systems for managing plant parasitic nematodes and soil-borne diseases. The current focus is on IPM components such as solarization, biocontrol agents, and improvement of application technology of pesticides and biologicals. A field trial with carrots in the Imperial Valley demonstrated that solarization under California inland desert conditions can be very effective against a wide range of soil-borne pests and pathogens. Soil fumigation with metham sodium at label rate was less effective and did not significantly increase the efficacy of solarization when used in combination at a lower rate. A root-colonizing bacterium, Pseudomonas fluorescens BL915, protected various seedlings from damping-off caused by RHIZOCTONIA SOLANI. Spontaneous pleiotropic mutants fail to synthesize a number of antifungal factors such as chitinase, HCN, pyrrolnitrin and their biological control potential is greatly reduced. A genomic DNA fragment was isolated and when introduced into the mutants, restored the lost functions including their biocontrol activities. Furthermore, a new application system for turf pesticides was developed which showed potential to reduce the overall use of nematicides on golf courses and other turf areas by targeting spots with high nematode population densities.

Impacts
(N/A)

Publications

• HILL, D.S., J.I. STEIN, N.R. TORKEWITZ, A.M. MORSE, C.R. HOWELL, J.P. PACHLATKO, J.O. BECKER, and J.M. LIGON 1994. Cloning of genes involved in the synthesis of pyrrolnitrin from PSEUDOMONAS FLUORESCENS and the role of pyrrolnitrin synth.
• GAFFNEY, T.D., S.T. LAM, J. LIGON, K. GATES, A. FRAZELLE, J. DI MAIO, S. HILL, S. GOODWIN, N. TORKEWITZ, A.M. ALLSHOUSE, H.-J. KEMPF, and J.O. BECKER 1994. Global regulation of expression of antifungal factors by a PSEUDOMONAS FLUORESCENS.
• MUNDO-OCAMPO, M., J. O. BECKER, and J. BALDWIN 1994. Occurrence of BELONOLAIMUS LONGICAUDATUS in turf in the Coachella Valley. Plant Disease 78: 529.
• BECKER, J.O. 1994. A new nematicide application device for targeted spot treatment against the sting nematode in turf. Proceedings Second National IPM Symposium/Workshop, Las Vegas, 143.