Progress 10/01/11 to 09/30/14

Outputs
Target Audience: The target audiences were western region pecan growers and pecan researchers. 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? Grower organization meetings; grower tours of research plots. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? Fertigation of ZnEDTA has been proven to be effective, even in highly calcareous southwestern soils. This method is rapidly being adopted by the industry in Arizona where it is appropriate (sprinkler or drip irrigated orchards). Our hedging frequency data provide growers with information on which hedging can be based. We have elucidated effects of hedging on nut yield and quality and provided an economic analysis of tree responses.

Publications

• Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Hedge Pruning Pecan Trees. First South African Pecan Conference, Hartswater, SA. 2/12/2013
• Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Importance of Soil Preparation and Chemical Corrections for Pecan Production, First South African Pecan Conference, Hartswater, SA. 2/12/2013
• Type: Theses/Dissertations Status: Published Year Published: 2013 Citation: Placide Hiol, MS Thesis, University of Arizona. Economic Evaluation of he Pruning Frequency of Pecans
• Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: New Mexico Pecan Growers Field Day. Las Cruces, NM 10/29/2013
• Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Can I Quit Spraying Zinc? Arizona Pecan Growers Association Conference, Tucson AZ 9/25/2013
• Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Zinc Management in Calcareous Aridisols Western Soil Science Society of America Conference, Tucson AZ 7/18/2013
• Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Nutrient Management in Pecans Western Nutrient Management Conference, Reno NV 3/2/2013

Progress 10/01/12 to 09/30/13

Outputs
Target Audience: The target audiences were western region pecan growers and pecan researchers. 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? Grower organization meetings; grower tours of research plots. What do you plan to do during the next reporting period to accomplish the goals? Continue research, data collection and information communication.

Impacts
What was accomplished under these goals? Fertigation of ZnEDTA has been proven to be effective, even in highly calcareous southwestern soils. This method is rapidly being adopted by the industry in Arizona where it is appropriate (sprinkler or drip irrigated orchards). Our hedging frequency data provide growers with information on which hedging can be based. We have elucidated effects of hedging on nut yield and quality and provided an economic analysis of tree responses.

Publications

• Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: New Mexico Pecan Growers Field Day. Las Cruces, NM 10/29/2013
• Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Can I Quit Spraying Zinc? Arizona Pecan Growers Association Conference, Tucson AZ 9/25/2013
• Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Zinc Management in Calcareous Aridisols Western Soil Science Society of America Conference, Tucson AZ 7/18/2013
• Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Nutrient Management in Pecans Western Nutrient Management Conference, Reno NV 3/2/2013
• Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Importance of Soil Preparation and Chemical Corrections for Pecan Production, First South African Pecan Conference, Hartswater, SA. 2/12/2013
• Type: Theses/Dissertations Status: Published Year Published: 2013 Citation: Placide Hiol, MS Thesis, University of Arizona. Economic Evaluation of he Pruning Frequency of Pecans
• Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Hedge Pruning Pecan Trees. First South African Pecan Conference, Hartswater, SA. 2/12/2013

Progress 01/01/12 to 09/30/12

Outputs
Target Audience: The target audience consists of pecan researchers, pecan growers and manager, primarily those located in the southwestern states of Texas, New Mexico, Arizona, and California. 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? Growers have visited the research blocks, and several are expected to adopt this management method. Presentations: Zinc Management by Soil Application. Arizona Pecan Growers Association annual meeting. Tucson, AZ, September 21, 2012. Managing Salts in Irrigated Pecan Orchards. New Mexico Pecan Growers Field Day. Las Cruces, NM, November 1, 2012. Salinity. New Mexico Pecan Short Course. Las Cruces, NM, September 25-28, 2012. What do you plan to do during the next reporting period to accomplish the goals? Continue research, data collection, and information communication.

Impacts
What was accomplished under these goals? Foliar Zn levels responded positively to fertigated Zn-EDTA, demonstrating the efficacy of this approach. Visible Zn deficiency symptoms were eliminated or greatly reduced. Preliminary evaluation of leaf zinc concentrations suggests that the current recommendations of 40 to 50 ppm Zn are excessive.

Publications

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

Outputs
OUTPUTS: Results from this project were reported in several presentations to growers: Soil Applied Zinc. Western Pecan Growers Association annual meeting. Las Cruces, NM. Yield and Nut Quality of Hedge Pruned Pecans in Arizona. Arizona Pecan Growers Association annual meeting, Tucson, AZ. Yield and Nut Quality of Hedge Pruned Pecans in Arizona. XII Simposio Internacional de Nogal Pecanero, Hermosillo, Mexico. Effectiveness of Soil-Applied Zinc for Pecans. Western Nutrient Management Conference, Reno, NV. Data were also shared directly with growers involved in this project. PARTICIPANTS: One graduate student worked on this project during the current reporting perios. TARGET AUDIENCES: Pecan growers in the desert southwest (Arizona, New Mexico, Texas, Sonora Mexico) are targets of this project, as are pecan processing companies within this area. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Studies of methods for applying zinc to pecan trees have resulted in changes in on-farm practices. For example, our research showing the effectiveness of zinc EDTA applied to the root zone at planting has resulted in some large growers adopting this practice. Early results of research on irrigation applied zinc EDTA have been positive and this practice has the potential to significantly change pecan fertilization practiced in the desert southwest. Growers are very interested in studies of mechanical hedge pruning. This has become a common practice, however, almost no data exist to inform growers of the efficacy of hedge pruning.

Publications

• Nunez-Moreno, H., J.L. Walworth, and A.P. Pond. 2011. Field Identification and Characterization of Manganese Toxicity in Western Schley Pecan Trees. Acta Horticulturae of the Mineral Nutrition Session (Lisboa 2010 IHC Congress.
• J.L. Walworth, A.P. Pond, and M.W. Kilby. 2011. Leaf Sampling Guide with Interpretation for Arizona Pecan Orchards. The University of Arizona Cooperative Extension Publication AZ1410, University of Arizona, Tucson, AZ.

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

Outputs
OUTPUTS: 1. A soil-applied Zn study was started in 2005. Zn sulfate (74 kg Zn/ha) and Zn EDTA (19 kg Zn/ha) were soil banded on established Wichita pecans growing in a calcareous soil. Following this one-time treatment, foliar Zn levels in the Zn-EDTA treatments have been higher than those in untreated trees in approximately 25% of the monthly leaf samples. In 2009, leaf Zn concentrations were not significantly different in the various treatments. Foliar Zn levels increased annually during the first three years of the study in all trees, perhaps due to a shift to organic production methods. Yields have not been affected by treatments. Monitoring of these plots will be discontinued. 2. A study was initiated in 2006 to investigate the effect of combinations of Zn sulfate and animal manure on Wichita pecans. Initial treatments were: manure (12 ton/ha), manure plus Zn (12 ton/ha plus 129 kg of Zn/ha as ZnSO4), and an untreated control. In 2007, two more treatments were added with doubled manure and Zn rates. Treatments were re-applied in March 2009. As in 2008, the manure 2x plus Zn 2x treatment had significantly higher leaf Zn concentrations than the control treatment or the treatments receiving only manure. 3. A corollary study was started in February 2008 on potted one-year old Wichita pecan trees planted in 40 L containers filled with calcareous soil. Treatments included an untreated control, soil-applied Zn sulfate, Zn EDTA, Zn Avail, manure, manure plus Zn sulfate, and foliar applied Zn sulfate. The manure application rate was 11.4 ton/ha, and the Zn application rate was 74 kg Zn/ha for each material. The foliar sprayed solution was ZnSO4 (0.24% w/v) plus urea ammonium nitrate (0.25% v/v). Soil treatments were applied once on April 4. Foliar sprays were applied every three weeks from. In the first year, plant growth (height and stem diameter) was not affected significantly by treatments. but foliar Zn concentrations were greatly elevated by application of ZnEDTA to the soil or ZnSO4 to the foliage. In the second year following soil treatments, however, foliar Zn levels in trees treated with ZnEDTA were not significantly greater than those of untreated trees. Soil sorption studies conducted to determine the effect of Zn source indicated that soil adsorption of Zn from Zn EDTA solutions was insignificant. It is believed that the leaching that occurred during irrigation of the pots resulted in leaching of ZnEDTA from the soil. However, leachate samples were not collected during the study. 4. In 2009 a field Zn uptake study was initiated in a newly planted orchard. Young Wichita trees were treated during transplanting with: Zn-EDTA (two rates), pisolithus, scleroderma, or a combination of pitholithus and scleroderma. Leaf samples were collected from the trees on September 24, 2009. Although the mycorrhizal treatments did not affect foliar Zn concentrations, application of the higher rate (70 ml/tree) of ZnEDTA increased foliar Zn to 56 ppm compared to 27 in the untreated trees. Trees treated with 35 ml/tree of ZnEDTA had a foliar Zn of 33 ppm, which was not significantly different than the untreated controls. PARTICIPANTS: This research is conducted in collaboration with Dr. Bruce Wood Southeastern Fruit and Tree Nut Research Laboratory, USDA-ARS and in coordination with Dr. Richard Heerema, Extension Specialist, New Mexico State University. TARGET AUDIENCES: The target audiences of this program include soil and plant researchers, particularly those working with tree crops in the Southwestern United States, as well as growers in this region. PROJECT MODIFICATIONS: A study is being set up in a new orchard that will allow us to apply ZnEDTA through micro-sprinklers in a newly planted orchard of Wichita trees. The infrastructure of this study is being installed at the present time. Trees will be planted in the winter of 2010-2011, and treatments will be initiated in the 2011 growing season.

Impacts
Our research has shown that, with proper management strategies, soil-applied zinc can be successful on Southwestern pecans. However, we have not yet been able to prove the efficacy of specific practices to the point that grower practices will change significantly. Some growers are starting to apply zinc directly to soil, and we are recommending soil-applied zinc at the time of planting in newly-established orchards.

Publications

• Nunez-Moreno, H., J.L. Walworth, A.P. Pond, and M.W. Kilby. 2009. Soil Zinc Fertilization of Wichita Pecan Trees Growing under Alkaline Soils Conditions. HortScience 44(6):1736-1740.
• Nunez-Moreno, H., J.L. Walworth, A.P. Pond. 2009. Manure and Soil Zinc application to Wichita Pecan Trees Growing under Alkaline Conditions. HortScience 44(6):1741-1745.

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

Outputs
OUTPUTS: A field study documenting and describing manganese toxicity in pecans was completed in 2008, and a manuscript is in preparation. Fate and utilization of several zinc materials applied to a calcareous soil was studied. Zinc uptake evaluated with young trees grown in pots, and zinc sorption by this soil was described by developing adsorption isotherms. Results from this study are being prepared for publication. A field study was also set up based on results of the pot study. During establishment of a new orchard, soil treatments were applied, consisting of: zinc EDTA at two application rates (35 or 70 mls of 9% Zn-EDTA per tree), or spores of either of two mycorrhizal fungi; pisolithus (5 g per tree) or schleroderma (3 g per tree). Zinc uptake by and growth of the treated trees will be monitored in future years. PARTICIPANTS: Individuals: Mr. Andrew Pond Mr. Humberto Nunez Dr. Richard Heerema Dr. Bruce Wood Organizations: New Mexico State University USDA Southeastern Fruit & Nut Research Laboratory, Byron, Georgia Instituto Nacional de Investigaciones Forestales, Agricolas, y Pecuarias (INIFAP)(Mexico) TARGET AUDIENCES: Key targets for this project include: pecan growers in the arid west (primarily Arizona, but also including California, New Mexico, Texas, Arkansas, and Northern Mexico), advisors working with pecan growers, Cooperative Extension personnel, and scientists involved in pecan research. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.

Impacts
Results of studies including nitrogen rate, soil-applied zinc, and leaf tissue analyses were presented to pecan growers at the Western Pecan Growers Association annual meeting, the Arizona Pecan Growers Association annual meeting, NOGATEC in Torreon, Mexico, and in Hermosillo, Mexico. Results from nitrogen rate are being used to refine fertilizer recommendations for producing trees. Data from a preliminary soil-applied zinc pot study were used to develop an applied field study.

Publications

• J. Walworth, A. Pond, H. Nunez, and M. Kilby. Nutrient Balance for Pecans. 2008. Proceeding of Reunion Tecnica Internacional de Nogal Pecanero. Memoria Tecnica 27: 26-35.

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

Outputs
OUTPUTS: We have completed three years of a preliminary field study to assess the ability of soil-applied zinc materials to supply zinc to established pecan trees, and to determine the long-term effect of these treatments. In March 2005, we initiated treatments in a commercial orchard with young pecan trees. This test compares zinc sulfate (ZnSO4), the zinc fertilizer most commonly used for foliar applications, and ZnEDTA, a chelated form of zinc. Leaf zinc concentrations were highest in the trees treated with the zinc-EDTA, although generally not statistically greater than in other treatments. Although leaf zinc levels have been elevated in the zinc-EDTA treated trees, and it is hoped that leaf zinc levels will continue to rise in subsequent years, leaf zinc levels have not yet reached the 50 ppm target threshhold. A second field study has been initiated to evaluate efficacy of soil-applied zinc sulfate with and without co-applied animal manure. This study has been initiated to test the possibility of using naturally-occurring organics to facilitate zinc uptake by pecans. First year data from this multi-year study showed no differences between treatments. An additional study has been initiated to evaluate efficacy of zinc sources in a pot study. Several zinc-containing materials have been applied to soil in pots containing young grafted pecan trees. Treatments include a control (no zinc applied), soil applied zinc sulfate, zinc-EDTA, manure with zinc sulfate, manure alone, zinc-loaded AVAIL, and foliar zinc sulfate. Results are not yet available from this study. Nitrogen requirements of mature pecan trees are being studied in a commercial pecan orchard where blocks were treated with varying rates of nitrogen fertilizer. Treatments were initiated beginning in the 2005 growing season. Three rates of nitrogen are being applied (seasonal total applied nitrogen = 115, 260, 400 kg/ha N) as a split broadcast application prior to each irrigation. All treatments are replicated three times. 2005 was an off year. Mean yields ranged from 825 to 1050 kg/ha and were not significantly different among treatments. Mean leaf nitrogen was 3.0% and was not affected by treatments. In contrast 2006 was an on year. Nut yields were highest in the trees receiving the lowest level of N fertilization and lowest in those receiving the highest rate of N fertilizer. The percentage of grade-out was significantly affected as well. The nuts not rated as good were all stick-tights. In the 118 kg/ha N treatment about 8% of the nuts were stick-tights compared to 28% in 236 kg/ha N treatment and 55% in the 354 kg/ha treatment. In the good nuts, percent kernel was unaffected. Because of the strong influence of N on grade-out, the kernel yield was even more affected by N treatment than whole nut yield. The responses of nut yield, grade-out, and kernel yield were all linearly related to N application rate. In neither 2005 nor 2006 was nut size was significantly affected by N application, although in both years, there was a non-significant decrease nut size with increasing N rate. PARTICIPANTS: Dr. Bruce Wood, USDA-ARS Southeastern Fruit and Tree Nut Research Laboratory is a collaborator in these studies, and provides financial support for the research. TARGET AUDIENCES: The target audience for this project consists of commercial pecan growers in the southwestern US, including Arizona, New Mexico, and Texas.

Impacts
Our zinc studies are still preliminary. We have not developed techniques that can be adopted by commercial growers. We are expanding these studies in cooperation with researchers in other states. Nitrogen studies need to be continued for at least two more years to encompass at least two two-year on-off yield cycles.

Publications

• J.L. Walworth and A.P. Pond. 2006. Zinc Nutrition of Pecans Growing in Alkaline Soils. Pecan South 39(5):14-22.
• Pond, A.P., Walworth, J.L., Kilby, M.W., Gibson, R.D., Call, R.E., and Nunez. 2006. Leaf nutrient levels for pecans. HortScience 41(5):1339-1341.
• Walworth, J.L. and Pond, A.P. 2006. Zinc nutrition of pecans growing in alkaline soils. Pecan South 39(5): 14-22.
• Walworth, J.L., Pond, A.P., Sower, and Kilby, M.W. 2006. Fall-applied foliar zinc for pecans. HortScience 41(1): 275-276.

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

Outputs
In the past year four field experiments were conducted, investigating the use of soil-applied zinc, combinations of zinc and animal manure, alternate panel irrigation, and varying levels of nitrogen application. One peer-reviewed article, one popular press article, and two Cooperative Extension bulletins were published, and talks were presented at professional and grower meetings.

Impacts
This applied research is designed to generate recommendations and test new practices for pecan production in the desert southwest of the United States and in northwest Mexico. It is hoped and expected that successful practices will be adopted by progressive growers.

Publications

• A.P. Pond, J.L. Walworth, M.W. Kilby, R.D. Gibson, and R.E. Call. 2006. Leaf Nutrient Levels for Pecan in Southern Arizona. HortScience 41(5):1339-1341
• J.L. Walworth, A.P. Pond, and M.W. Kilby. 2006. Leaf Sampling Guide with Interpretation for Arizona Pecan Orchards. The University of Arizona Cooperative Extension Publication AZ1410, University of Arizona, Tucson, AZ. http://cals.arizona.edu/pubs/diseases/az1410.pdf
• T.L. Thompson and J.L. Walworth. 2006. Salinity Management and Soil Amendments for Southwestern Pecan Orchards. University of Arizona Cooperative Extension Publication AZ1411, University of Arizona, Tucson, AZ. http://cals.arizona.edu/pubs/diseases/az1411.pdf

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

Outputs
Three field research trials were conducted in 2005 as part of this project: Soil Applied Zinc for Arizona Pecans, Water Use and Management in Arizona Pecans, and Determination of Nitrogen Requirements for Arizona Pecans. All are ongoing multi-year projects, and only preliminary results are available. Typically, Zn is applied to pecans foliarly, however this does not provide good Zn distribution within pecan trees. Soil Zn application is problematic because of the very low solubility of Zn in calcareous soils. We have initiated a study soil applied Zn. Zinc was applied in two bands, one on either side of the tree row, about four feet from the base of the tree, and about 7 inches deep. ZnSO4 was applied at a rate of 90 lbs of Zn/acre and Zn-EDTA was applied at a rate of 17 lbs Zn/acre. A third treatment consisted of trees that did not receive any Zn application. Each plot consisted of a single row of 15 trees and treatments were replicated four times in a randomized complete block design. Early results suggest that leaf tissue Zn is slightly higher in trees treated with Zn-EDTA than in the other two treatments. Water consumption is being estimated by soil moisture measurements and the effects of three irrigation regimes on nut yield and quality are being monitored. Goals of the study are 1) to evaluate pecan tree ET under commercial Arizona production conditions, 2) to determine crop coefficients (Kc) for pecans grown in Southern Arizona, 3) to monitor pecan tree phenology and to relate phenology to weather conditions through mathematical modeling, and 4) to evaluate the effects of varying irrigation regimes during the nut sizing period (late May through July) on nut production and quality. Nitrogen application rates are being studied in a flood irrigated orchard. Three rates of nitrogen are being applied (seasonal total applied nitrogen = 100, 225, 350 lbs N/acre) as split broadcast applications prior to each irrigation. First year data indicate no yield or quality differences among treatments. In the second year of this study, number of blooms per branch will be measured in upper and lower portions of the tree by visual inspection. Nuts will be commercially harvested individually from each plot by mechanically shaking trees, then collecting nuts with field harvesting equipment. Nuts will be weighed and yield will be recorded. Subsamples of nuts will be weighed to determine average nut weight, and shelled to determine percent kernel in the harvested nuts from each tree.

Impacts
This project is designed to provide improved management guidelines for pecan growers, with emphasis on fertility requirements and fertilizer recommendations, and irrigation management. It is expected that, if soil applied Zn applications prove efficacious, growers will adopt this technique. The goal of the nitrogen study is to reduce excessive nitrogen applications, whereas irrigation research is expected to result in more efficient use of irrigation water.

Publications

• J.L. Walworth, A.P. Pond, G.J. Sower, and M.W. Kilby. 2006. Fall-Applied Foliar Zinc for Pecans in the Desert Southwest. HortScience: in press.
• Pond, A.P., J.L. Walworth, M.W. Kilby, R.D. Gibson, and R.E. Call. 2006. Leaf Nutrient Levels for Pecans. HortScience: accepted.
• Walworth, J.L. 2005. Pecan Leaf Nutrition Status. Western Pecan Growers Conference Proceedings. pp. 45-50. Las Cruces, NM. March 6-8, 2005.
• Walworth, J.L., G.J. Sower, A.P. Pond, M.W. Kilby, R.D. Gibson, R.E. Call, and B. Lewis. 2005. Pecan Leaf Nutrition Status. Western Nutrient Management Conference Proceedings 6:121-128. Salt Lake City, UT. March 3-4, 2005.
• Walworth, J.L. 2005. Late Season Zinc Applications for Pecans, New Mexico Pecan Growers Field Day Abstracts, April 28, 2005. Las Cruces NM.

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

Outputs
Three field studies were conducted as part of this project in 2004. A two year survey of commercial pecan orchard was conducted, which included monitoring of 135 individual trees of Western Schley pecans at 27 locations in Arizona. Data collected for these trees included soil properties, leaf nutrient levels, nut yield and quality, and cultural practices. These data are being used to generate nutrient standards for interpretation of plant tissue analyses. 2004 was the second and final year of a field study evaluating effectiveness of late-season foliar zinc applications. Treatments included an untreated control, 12.5 or 25 lbs Zn/acre applied late in the season (October), or 12.5 or 25 lbs Zn/acre applied in split applications applied every two weeks over a 10 week period (the standard practice in Arizona). In both years, late-season zinc applications increased bud and twig zinc contents in the subsequent spring, but did not increase leaf zinc in the subsequent growing season (first year only - second year analyses not completed). Two year average yields were not statistically affected by zinc treatments. Irrigation rates were varied during the nut sizing period that extends from approximately mid-May to late July. Irrigation rates consisted of the current grower rate (approximately 3.2" every 8 days or 0.4"/day) and a 20% increase and 20% decrease from the grower rate. Adjustments from grower irrigation rate were accomplished by adjusting nozzle size in the sprinklers. Although differences in first year data were not statistically significant, trends suggest that yield (both lbs nuts/acre and lbs kernels/acre) and number of nuts/acre increased with increasing irrigation water. Nut fill (% kernel) increased with decreasing irrigation, but not enough to compensate for the decreased number of nuts.

Impacts
In 2005, leaf tissue nutrient standards will be published for use in interpreting leaf analyses. Late-season zinc applications will not be recommended to growers.

Publications

• Walworth, J.L., G. Sower, A. Pond, M. Kilby, R. Gibson, R. Call, and B. Lewis. 2005. Pecan Leaf Nutrition Status. 2005. Western Nutrient Management Conference Proceedings, Vol. 6. pp. 121-128. March 3-4, 2005. Salt Lake City, UT.
• Walworth, J.L. Pecan Leaf Nutrition Status. 2005. 34th Annual Western Pecan Growers Conference Proceedings. March 6-8, 2005. Las Cruces, NM.