Source: MICHIGAN STATE UNIV submitted to
ORGANIC DRY BEAN PRODUCTION SYSTEMS
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
Reporting Frequency
Annual
Accession No.
0222485
Grant No.
2010-51300-21224
Project No.
MICL05040
Proposal No.
2010-01904
Multistate No.
(N/A)
Program Code
113.A
Project Start Date
Sep 1, 2010
Project End Date
Aug 31, 2015
Grant Year
2010
Project Director
Renner, K. A.
Recipient Organization
MICHIGAN STATE UNIV
(N/A)
EAST LANSING,MI 48824
Performing Department
Plant, Soil and Microbial Science
Non Technical Summary
Crops compete with weeds. The goal in all production systems is to tip the competitive balance to favor the crop over the weed. The choice of crop variety is of utmost importance in this battle. If a variety is "competitive" it will emerge well under stressful conditions, capture moisture, light, and available nutrients, suppress weeds, and be tolerant of insect pests and diseases. For centuries plant breeders have been selecting for varieties that have the highest yields under pest-free and nutrient-rich conditions. Organic farmers need varieties that perform well under their production systems which may differ in nutrient availability and pest pressure compared with conventional systems. In conventional production systems navy bean cultivars yield more than black bean cultivars. However, black beans produced greater yields than navy beans in organic trials. These yield differences in dry bean class and variety may in part be due to differences in nitrogen fixation and uptake by bean root systems. Nitrogen availability in organic systems is largely dependent on the crop rotation, including the planting of cover crops. Red clover is a common cover crop which when tilled into the soil supplies an available form of nitrogen for the following crop. Rye and oilseed radish are not legumes, but both may increase nitrogen availability to dry beans by mineralization of nitrogen during the summer months. By researching the incorporation of cover crops into organic dry bean production systems we will determine which cover crop (or lack thereof) supports the nodulation and uptake of nitrogen for optimum seed yield in organic dry bean production systems. Including cover crops prior to planting dry beans may help in weed suppression. Some cover crops such as cereal rye suppress germinating weed seedlings due to release of allelopathic compounds. However, weed suppression by these compounds is short-lived and therefore producers must manage emerging weeds by other means, including rotary hoeing and cultivation. The vigor of the dry bean variety is very important because it is difficult to cultivate weeds when the crop is not growing vigorously. Furthermore, cover crop residues may assist or hinder weed management by mechanical methods in the weeks following dry bean planting. On-farm trials will provide much needed information on how to manage weeds in cover crop/no cover crop residue situations in organic dry bean production. Organic dry bean producers must also manage insect and disease pests. In this regard cover crops can be either a help or a hindrance. For example, "Colonel" oilseed radish is a well known variety that suppresses nematode pests. On the other hand, if beans are planted too close to the incorporation of a cover crop insects like seed corn maggot can become a problem. Western bean cutworm is a relatively new pest that is of concern to all dry bean producers. It is currently unclear what role dry bean variety and cover crops play in negating or enhancing the infestation of this pest.
Animal Health Component
(N/A)
Research Effort Categories
Basic
50%
Applied
50%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
1021410106030%
1021410108030%
1021410113010%
1021410114010%
2161410106020%
Goals / Objectives
Our long term goal is to provide dry bean variety and pest management recommendations to improve organic dry bean production systems. Dry bean farmers (navy, black, pinto, kidney, cranberry, etc.) are "row crop" growers, rotating fields with corn, soybeans, and small grains. Dry beans are nodulating legumes but require additional nitrogen for optimum seed yield. Cover crops are an important component of organic production systems to suppress weeds, improve soil quality, and provide nutrients, including nitrogen, for optimum crop production. We need to develop dry bean varieties suited to organic production systems, and provide dry bean growers with weed and pest management recommendations to increase organic acreage and improve the profitability of organic dry bean production. Long term goals: -Provide information regarding varieties of dry beans that are best suited to organic production -Determine dry bean varieties that make the best use of atmospheric and soil-available nitrogen -Develop recommendations regarding the best species of cover crop(s) to plant prior to dry bean for synchronization of nitrogen release by the cover crop residues and nitrogen demand by the dry bean -Improve recommendations for weed and insect management in organic dry bean production following cover crops -Expand the dry bean breeding program to select for characteristics that favor organic cultural practices Our proposal has six objectives that encompass our overall goal to provide U.S. dry bean growers with variety, cover crop, and pest management recommendations to improve organic dry bean production systems. Our proposal includes on-farm research on six organic farms in Michigan, as well as research at two MSU experimental research stations with certified organic ground. We have numerous stakeholders involved in our proposal, including six organic producers that will have on-farm research during each year of the project, personnel at our university research locations, extension educators, farmers, and members of the Michigan Dry Bean Commission and the U.S. Dry Bean Council. Our specific objectives are as follows: 1. Identify dry bean varieties that are best suited for organic production, including nitrogen demand and nitrogen fixation through nodulation (1a and 1b), the ability to tolerate prolonged mechanical weed management (1a), and dry bean production and seed yield in cover crop systems (1a). 2. Measure soil nitrogen availability in dry beans planted in rotation following cover crops. 3. Determine if cover crops prior to dry beans influence weed emergence and growth and mechanical weed management 4. Evaluate key insects pests in organic dry bean production as influenced by variety and cover crops prior to planting. 5. Expand dry bean breeding activities to select for traits that are best suited to organic production. 6. Educate growers and the agricultural community on organic dry bean production through extension efforts.
Project Methods
Overall approach for Objectives 1a, 2, 3, and 4: This study has two types of experimental sites: MSU certified organic research land and on-farm organic grower land. The cover crops oilseed radish and cereal rye will be seeded following oats in the year prior to dry beans. Red clover will be frost-seeded into the oats. The cover crops will winter-kill or be controlled by tillage in the spring. The on-farm growers will select only one cover crop to plant. Dry beans will be planted in June and harvested at maturity. Zorro and Jaguar black bean and Vista and R99 navy bean will be planted at the two MSU research farm sites. At the on-farm locations, Zorro black bean and Vista navy bean will be planted. The dry beans will be harvested by hand at all plot locations. Seed weight, nitrogen, and percent moisture, will be determined. Objective 1a. All sites will be visited each week to manage the observations and measurements as outlined above. Objective 1b. At one MSU site and one on-farm site, an elite group of 30 advanced navy and black bean breeding lines will be evaluated under organic production management systems to identify superior individuals best adapted to this production system. Measurements will include: stand counts, flowering, maturity, plant height, lodging, occurrence of disease, yield, nitrogen fixation, total nitrogen, % protein, and processing quality. Objective 2. Soil nitrogen data, coupled nitrogen fixation capability will allow us to make recommendations about the importance of nitrogen and the timing of N availability in organic production systems with/without cover crops. Significant relationships between dry bean seed yield and soil nitrogen will be statistically determined. Objective 3. All cover crop planting and management information will be recorded in addition cover crop biomass, weed biomass and emergence, dry bean response to cultivation, and on-farm grower observations. Objective 4. At all locations and in all plots, insect pressure will be recorded regularly, specifically looking for seed corn maggot, armyworm, leaf hopper, bean leaf beetle, Japanese beetle, and western bean cutworm. These observations will be used to determine resistant varieties of beans and if and when organic herbicides need to be applied. All insect data will be analyzed to determine the influence of cover crop and dry bean variety on insects. Objective 5. A combination of field and greenhouse screening will be used to phenotype populations for ability of individual RILs to fix N. Winter nurseries at the Univ. of Puerto Rico, Mayaquez will be used to gather additional data. To complement this work the same RIL populations will be genotyped with microsatellite markers to identify QTL associated with the nitrogen fixation trait. Significant QTL will be used in future breeding programs to improve the nitrogen fixation capacity in a broader range of bean seed types. Objective 6. The research-based information on dry bean production in organic systems will be delivered to growers and the agricultural community using various web-based and printed materials as well as through presentations.

Progress 09/01/10 to 08/31/15

Outputs
Target Audience:The target audience was organic growers in the Midwest, and those interested in organic production throughout the U.S., including other researchers. We had field days in Michigan that farmers attended in 2013 and 2014. We had a webinar in 2014 that was attended by 105 people (live), and archived on the eOrganic web site. We have presented papers at various conferences on the results of this research, regionally and nationally. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?We presented a webinar in March 2014 'Breeding efforts and cover crop choices for improved organic dry bean production systems in Michigan.' We had farmer field days in 2013. We presented our results at professional meetings in 2013 and 2014 and at the Organic Ag Research Symposium at Lacrosse WI in 2015. Two Ph.D. student disserations were published from this research. How have the results been disseminated to communities of interest?We presented a webinar in March 2014 'Breeding efforts and cover crop choices for improved organic dry bean production systems in Michigan.' We had farmer field days in 2013. We presented our results at professional meetings in 2013 and 2014 and at the Organic Ag Research Symposium at Lacrosse WI in 2015. Two Ph.D. student disserations were published. Two refereed journal articles are in press; three additional refereed journal articles are planned for 2016. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Seventy-nine black and navy bean elite breeding lines and commercial varieties were evaluted for yield in certified organic fields atthree locations over a three year period. The same genotypes were also assayed for nodulation characteristics. The percent of nitrogen in the grain derived from the atmosphere in the greenhouse was correlated with seed yield, N grain yield, and field N fixation, suggesting that enhanced symbiotic nitrogen fixation traits could improve productivity in organic systems. The inheritance of enhanced symbiotic nitrogen fixation was investigated in the greenhouse and in the field, and a quantitative trait loci (QTL) analysis of the phenotypic data was conducted using single nucelotide polymorphism (SNP) markers developed through the BeanCAP. Nineteen QTLs associated with symbiotic nitrogen fixation traits were identified. The majority of QTLs associated with genes expressed in the root or nodule were derived from Puebla 152 while QTLs associated with genes with enhanced expression in pods were associated with Zorro black bean. This follows a pattern where Puebla 142 has superior symbiotic nitrogen fixation ability, whereas Zorro is highly efficient in partitioning the fixed N into the seed. The QTLs described will serve as potential targets for improved nitrogen fixation in adapted commercial dry bean genotypes. In our three year field study, navy bean and black bean responded to cover crops similarly and showed few differences with regard to nodulation, tolerance of mechanical weed control, and yield. The non-nodulating variety R-99 had less total grain N and yield, showing the benefit of symbiotic nitrogen fixation. Cover crops influenced soil inorganic N. Soil inorganic N increased following red clover by as much as 34 kg/ha at planting and 55 kg/ha at the V2 dry bean growth stage compared with the no cover crop control. Bean yield did not increase compared to the no cover control, but grain N increased by up to 32% in some site-years following red clover. Cereal rye reduced soil inorganic N in some instances and caused early maturity of beans in two of six site-years. Grain N was not affected. Oilseed radish had very little impact on soil inorganic N, bean maturity, yield or grain N. Cereal rye and oilseed radish did not impact weed biomass during the dry bean growing season. A red clover cover crop increased weed biomass in dry bean when soil inorganic N increased due to a clover biomass that exceeded 5 Mg/ha. Weed seed persistence was influenced by cover crop residues in some years. Common lambsquarters seed persistence decreased in one year following red clover; giant foxtail and velvetleaf seed persistence increased in one year following cereal rye, as compared to the no cover control. Western bean cutworm damage was not influenced by dry bean variety or presence of a cover crop in the one year of research.

Publications

  • Type: Theses/Dissertations Status: Accepted Year Published: 2015 Citation: Hill, E. 2015. Cover crop influence on nitrogen availability, weed dynamics, and dry bean (Phaseolus vulgaris) characteristics in an organic system. pp. 224.
  • Type: Journal Articles Status: Awaiting Publication Year Published: 2015 Citation: Hill, E.C., K.A. Renner, C. L. Sprague, and A. S. Davis. 2015. Cover crop impact on weed dynamics in an organic bean system. Weed Sci. 64: in press.
  • Type: Journal Articles Status: Awaiting Publication Year Published: 2015 Citation: Hill, E. C. , K. A. Renner, and C. L. Sprague. 2016. Cover crop impact on nitrogen availability and dry bean in an organic system. Agron. J. 108:1-13.
  • Type: Theses/Dissertations Status: Accepted Year Published: 2015 Citation: Heilig, J. A. 2015. QTL Mapping of symbiotic nitrogen fixation in dry bean: evaluation of dry bean genotypes under organic production systems.


Progress 09/01/13 to 08/31/14

Outputs
Target Audience: Target audience has been organic growers in Michigan, those interested in organic production throughout the US, including other researchers. We had field days where farmers attended and we had a webinar that was attended live by 105 people and was archived on the eOrganic web site. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? eOrganic webinar was produced byour research group produced in March 2014, entitled, “Breeding efforts and cover crop choices for improved organic dry bean production systems in Michigan.” How have the results been disseminated to communities of interest? eOrganic webinar by our research group was produced in March 2014, entitled, “Breeding efforts and cover crop choices for improved organic dry bean production systems in Michigan.” . In 2014 we presented ata meeting by an organic processor group in MI that was attended by 60 individuals. We also presented at a Bean Improvement Cooperative meeting in October. What do you plan to do during the next reporting period to accomplish the goals? We will be completing our last year and disseminating our results at professional meetings, submitting to refereed journals the results of our research, and presenting to growers in various venues, including the Organic Ag Research Symposium in February 2015 at Lacrosse, WI

Impacts
What was accomplished under these goals? Our dry bean variety research suggests that black beans tend to yield more than navy beans in organic production systems. The nitrogen derived from the atmosphere does not appear to differ between black and navy bean genotypes indicating that perhaps other mechanisms may be involved in the yield difference seed in black and navy beans. Selection of appropriate dry bean varieties for resistance to diseases such as common bean blight is important to help improve yield. Several of the lines from the Puebla 152/Zorro population (such as B11603, B11551, and B11569) produced above average yields for the populationwhile half of the nitrogen found in the seed was derived fromthe atmosphere through fixation. Cover crops sometimes altered the soil environment during the dry bean growing season by changing soil moisture at planting and by influencing soil inorganic nitrogen throughout the growing season. Soil inorganic nitrogen often increased following red clover (< 2.5 tons acre-1 dry biomass at the time of incorporation) compared with the no cover crop control, resulting in some instances in increased weed density and biomass, increased chlorophyll content in bean leaves and greater grain nitrogen content; dry bean yield however was not affected. Cereal rye reduced soil inorganic nitrogen and bean leaf chlorophyll in some instances, and caused early maturity of the beans. At maximum biomass production (5.4 tons acre-1), rye reduced dry bean yield. Oilseed radish occasionally increased inorganic nitrogen availability and populations at the V2 dry bean stage, but had no impact on nodule numbers, percent nitrogen derived from the atmosphere, chlorophyll readings, maturity, yield, or grain nitrogen.

Publications

  • Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Hill, E., K. Renner, and C. Sprague. 2014. Impact of cereal rye and red clover on weed seed mortality. Weed Science Society of America annual meeting. 63. Vancouver, BC. Poster.


Progress 09/01/12 to 08/31/13

Outputs
Target Audience: Organic producers of dry edible beans, agronomists, and other researchers and extension personnel in Michigan and the U.S. were target audiences with presentations during this reporting period. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Nothing Reported How have the results been disseminated to communities of interest? We have presented at professional society meetings the results of our research and will continue to do so. We have held organic grower field days in MI; in the summer of 2013 we had four field days where a total of 70 organic producers attended. We will analyze and summarize three years of research data in the next nine months and submit our data for publication in refereed journals and provide information to farmers throughout the U.S. in an appropriate format. What do you plan to do during the next reporting period to accomplish the goals? We have presented at additional professional society meetings in late fall 2013 and in 2014. We will summarize our data and publish in referred journals the results of our research. We will also present a summary of our data to organic producers during the next 9 month period.

Impacts
What was accomplished under these goals? 1) and 5) A black bean recombinant inbred line (RIL) population resulting from a cross of the landrace selection Puebla 152 and the commercial black bean variety Zorro was developed to study the genetics of BNF and transfer the enhanced BNF ability of Puebla 152 (Type III growth habit) into the efficient Zorro (Type II). RILs were genotyped using the SNP (single nucleotide polymorphism) markers developed by the BeanCAP project. Phenotypic data was recorded in the field, greenhouse, and lab. Quantitative trait loci (QTL) analysis for traits such as root biomass and distribution, biomass, and percent N derived from the atmosphere (Ndfa) associated with BNF was conducted. Agronomic and BNF traits tended to colocalize, with several QTL for traits such as shoot to root ratio, shoot height, N in biomass and harvest index all being located between SNP markers ss715645852 and ss715650565 on bean chromosome Pv01; maturity, Ndfa in roots, root biomass, and percent N in seed between SNP markers ss715647551 and ss715645213 on Pv03; percent N in biomass and vigor between SNP markers ss715645785 and ss715650222 on Pv06; yield and N yield in seed between SNP markers ss715645234 and 22715644972 on Pv07; harvest index, N yield in seed, Ndfa seed, and percent N in seed between SNP markers ss715648540 and ss715646686 and N yield in seed, percent shoot N, flowering, lodging, vigor, biomass, and N yield in seed between SNP markers ss715646764 and ss715648408 on Pv08. These QTL will be utilized in breeding future bean genotypes with enhanced BNF. 2) - 4) Bean chlorophyll meter readings were highest following a clover cover crop. Later in the season, at R5, beans following a rye cover crop had lower readings than the other covers. Soils samples throughout the season (and ion exchange resin samples, at some timings and locations) also support that there was more available nitrogen following a clover cover crop. A rye cover crop reduced the amount of available soil nitrogen to beans, particularly in the form of nitrate. Bean populations at V2 and at harvest were higher following rye and oilseed radish cover crops than clover and no cover. Bean yields were lowest following a rye cover crop, due to nutrient immobilization. Though beans following clover did not have improved yields compared with oilseed radish and no cover, analysis of the grain showed an increase of 6 μg N/mg of grain following clover. A third year of data collected in 2013 will be included in our final data analysis 6) Organic field tours were held at 4 locations with a total of 70 organic bean growers in attendance. Results of the research to date were discussed.

Publications

  • Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Taylor, E., K. Renner, and C. Sprague. 2013. Cover crop influence on weeds in organic dry beans. Weed Science Society of America annual meeting. 125 Taylor, E. K. Renner, and C. Sprague. 2013 Cover crop influence on weeds in organic dry beans. @013 Michigan State University Organic Reporting Session. Hill, E. 2013. Cover crop influence on organic dry beans (two years of OREI project results, third year observations). Plot tours at 3 locations attended by a total of 70 farmers


Progress 09/01/11 to 08/31/12

Outputs
OUTPUTS: This research includes the development of organic black and navy bean varieties, and research on organic production systems, including cover crops and their impact on nutrient and pest management. Seed classes that yielded well in the organic system in previous research included the black-seeded genotypes; black beans also had high seed N accumulation(36%). A field experiment was conducted at two Ag Bioresearch locations in Michigan in 2011 and 2012. The cover crops studied included: medium red clover, oilseed radish, and cereal rye; a no cover treatment was also included. Within each cover crop treatment there were four bean varieties: 'Zorro' and 'Black velvet' black beans and 'Vista' and 'R-99' (non-nodulating mutant) navy beans. In 2011, the clover cover crop and the no cover crop treatments (weed infestation only) had the greatest peak biomass production (3500 kg/ha) at the Kellogg Biological Station (KBS), followed by oilseed radish (2,200 kg/ha) and rye (1,800 kg/ha). At the Student Organic Farm (SOF), rye was not controlled in early spring because of continuous rainfall patterns, resulting in the greatest peak biomass. In both years, bean chlorophyll florescence at V2 was highest following a clover cover crop, though the difference between cover crop treatments was not always significant. Soil nitrogen was greater in in the clover treatments in both years at KBS and at the SOF in 2012 only, when measured at planting and when beans were at the second trifoliate growth stage. At the SOF, bean yields following oilseed radish (2,700 kg/ha), clover (2,300 kg/ha), and no cover (2,200 kg/ha) were higher than beans following rye (1,500 kg/ha) in 2011. Reduced bean yields following rye may be the result of rye reducing soil moisture early in the season and immobilizing nutrients. Cover crops did not influence bean yield at KBS in 2011. In 2012, bean yields were greater in the no cover and oil seed radish plots at the SOF; at KBS yields were greatest in the oil seed radish plots. PARTICIPANTS: Karen Renner James Kelly Christy Sprague Dale Mutch Dan Rossman Chris Difonzo Erin Taylor Jim Heilig TARGET AUDIENCES: Organic bean producers Farmers that utilize cover crops in bean production systems Agribusiness personnel in dry bean production regions PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
The results of this research will allow organic bean producers to choose bean classes and varieties that yield well in organic production systems. Organic growers will see the impact of cover crops on nutrient and pest management in organic production systems, allowing them to design a production system that optimizes nutrient and pest management and bean yield and quality.

Publications

  • Taylor, E., K. Renner, and C. Sprague. 2012. Cover crop influence on nitrogen availability for organic dry beans. ASA, CSSA, and SSSA International Annual Meeting. 141-3. Cincinnati, OH. Oral presentation.
  • Heilig, J.A., and J.D. Kelly. 2012. Performance of dry bean genotypes grown under organic and conventional production systems in Michigan. Agron. J.104:1485-1492. doi:10.2134/agronj2012.0082.


Progress 09/01/10 to 08/31/11

Outputs
OUTPUTS: Research at the Michigan State University Student Organic Farm (East Lansing, MI), at the Kellogg Biological Station (Hickory Corners, MI) during the 2010-2011 growing season, and at nine on-farm locations determined the effect of cover crops on weed suppression, nitrogen availability, dry bean populations, and yields in organic farming systems. Cover crops included medium red clover, oilseed radish, and cereal rye; and a no cover treatment was also included. On-farm locations planted one cover crop; research farm sites had all cover crops planted. At the research farms there were four bean varieties: Zorro and Black Velvet black beans and Vista and R-99 (non-nodulating mutant) navy beans. At the nine on-farm locations, Zorro black bean and Vista navy bean were planted in early to late June and harvested in late September and October. Seeding rates were 296,400 seeds ha-1, a 20% higher seeding rate than recommended in conventional dry bean production systems to account for crop removal with mechanical weed control measures. Weed biomass and populations by species were recorded at two times, 1) V2 bean stage- after early season weed management was complete (i.e. tined weeding and rotary hoeing) 2) R5 bean stage- following final cultivation. Throughout the course of the experiment several methods were used to monitor nitrogen availability, including the use of a chlorophyll meter at numerous stages of bean development (V2, R1, and R5). Dry bean populations were recorded at the V2 stage and at harvest prior to taking yields. There was a wide range of weed management practices at the nine farm locations. Weeds were effectively managed in organic black and navy bean production at six of the nine locations by rotary hoeing or tine weeding once, followed by either one or two cultivations. At three locations black beans yielded 3,100 to 3,500 kg ha-1, three locations had yields from 2,400 to 2,800 kg ha-1, and three locations had yields from 1,600 to 1,900 kg ha-1. The three low-yielding farms rotary hoed and cultivated more frequently than the other six farms because of greater weed populations as measured by weed biomass at the V2 growth stage of dry beans. There was only a significant difference among covers for weed suppression at the V2 bean stage at the KBS research location. At both the V2 and R1 stages, bean chlorophyll florescence was highest in the beans following a clover cover crop, though the difference was not always significant. At the Student Organic Farm, bean yields following oilseed radish were higher (2,700 kg ha-1), clover (2,300 kg ha-1), and no cover (2,200 kg ha-1) were higher than beans following rye (1,500 kg ha-1). These reduced yields could be the result of the rye reducing soil moisture early in the season and immobilizing nutrients. No differences in yield based on cover crop treatment were observed at the Kellogg Biological Station. Outputs: None to date. PARTICIPANTS: Karen Renner, Professor; Christy Sprague, Associate Professor; Erin Taylor, Research Assistant. TARGET AUDIENCES: Farmers PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
None to date. This project just started.

Publications

  • Taylor, E.C., K.A. Renner, and C. L. Sprague. 2011.Incorporating cover crops into organic dry bean production systems. Proc. North Central Weed Sci. Soc. 66:227.
  • Renner, K.A., E. C. Taylor, and C. L. Sprague. 2011. Organic Farmers Weed Control Strategies in Dry Beans. Proc. North Central Weed Sci. Soc. 66:2.