Source: OKLAHOMA STATE UNIVERSITY submitted to NRP
STUDIES OF ALTERNATE BEARING IN PECAN
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
COMPLETE
Funding Source
HATCH
Reporting Frequency
Annual
Accession No.
1003871
Grant No.
(N/A)
Cumulative Award Amt.
(N/A)
Proposal No.
(N/A)
Multistate No.
(N/A)
Project Start Date
Oct 1, 2014
Project End Date
Sep 30, 2016
Grant Year
(N/A)
Program Code
[(N/A)]- (N/A)
Recipient Organization
OKLAHOMA STATE UNIVERSITY
(N/A)
STILLWATER,OK 74078
Performing Department
Horticulture & Landscape Architecture
Non Technical Summary
This project address four issues related to pecan production. Those are 1) sulfur requirements for optimal production and appropriate fertilizer management to achieve this goal, 2) ground cover management to promote optimal pecan production, 3) protocols for effective application and management of phosphorus and potassium nutrition for pecan production, and 4) identification of the cause of blackened, necrotic basal ends of kernels of Pawnee cultivar, currently the most widely planted cultivar in the U.S.A. This problem renders affected nuts unmarketable. In affected areas the incidence of the malady varies among years and has ranged from none to over 50% of the nuts at the same orchard. It has been confirmed in orchards from Oklahoma west to California, but not east of Oklahoma.Sulfur Requirement: The initial phase of the project identified pecan orchards with the lowest leaf sulfur concentrations in Oklahoma. An appropriate orchard was chosen and various fertilizer sources and rates will be applied annually. Results of this study will establish the minimum leaf sulfur sufficiency level for optimal production and an appropriate fertility program.Ground Cover: Past projects have elucidated allelopathic interactions between certain ground covers and pecan, intensity of interference between herbaceous species and pecan, and spatial and temporal effects of ground covers on pecan. The current study expands or knowledge of ground cover interference on bearing pecans. This plot was establish at planting with various distances maintained vegetation free surrounding the pecan trees. Trees are now in their 7th year of production. Results to date have identified appropriate vegetation free area surrounding trees of various ages and have resulted. Optimal distances have resulted in up to 3 fold yield increases.Phosphorus and Potassium Management: Initial research identified symptomology and yield reductions associated with phosphorus and potassium shortages. Subsequent studies proved band application of these elements was successful in correcting shortages when traditional broadcast application was not. Current studies address optimal time of application, uptake interference when phosphorus and potassium are applied together and benefits of application within irrigation wetted zones vs. rain fed sites.Kernel Necrosis: Kernel necrosis describes kernels with blackened, necrotic tissue at the basal end of the kernel. I have been working on this problem several years, identifying the cultivars that are susceptible, areas of the U.S.A. where it has been confirmed, and developed and tested several hypotheses regarding its cause and cure. To date none of these have proven correct. Recent data suggests this may be associated with hyper sensitivity to arsenic by certain pecan cultivars. Elevating phosphorus is one method to mitigate arsenic toxicity. The current study evaluates band and broadcast phosphorus application to reduce or eliminate the incidence of kernel necrosis on 'Pawnee' pecan.
Animal Health Component
95%
Research Effort Categories
Basic
5%
Applied
95%
Developmental
0%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
1021211106075%
2131211106025%
Knowledge Area
102 - Soil, Plant, Water, Nutrient Relationships; 213 - Weeds Affecting Plants;

Subject Of Investigation
1211 - Pecan;

Field Of Science
1060 - Biology (whole systems);
Goals / Objectives
Determine the response to selected S sources and establish a minimum sufficiency concentration for leaf S concentration.Evaluate the efficacy of March vs. August applied (bud swell vs. late water stage fruit development) P and K.Determine the effects of bulk blended P and K band applied on one side of the tree vs. application of each element band applied on opposite sides of the tree.Determine the efficacy of P and K application within the wetted drip irrigation zone vs. application in the same location on the non-wetted side of the tree.Evaluate band applied and broadcast applied P to mitigate As toxicity, thus reducing the incidence of kernel necrosis on 'Pawnee' pecan.Continue evaluation of the vegetation free circle size on bearing pecan tree performance.
Project Methods
Sulfur This study will be conducted at an orchard owned and managed by the Samuel Roberts Noble Foundation. The orchard is located near Madill, OK. Trees at the beginning of the study will be 7-year-old 'Pawnee' grafted on 'Apache' seedling rootstocks in their first production year. Soil is a sandy loam and trees are irrigated with a drip system. Pest management follows Oklahoma guidelines. Treatments include a combination of nitrogen (N) and S. Treatments [in lbs of material per tree; urea 46% N, (NH4)2SO4 21%N + 24% S, elemental S 90% S] are 1) 0 urea + 0 (NH4)2SO4 + 0 elemental S, 2) 3 urea + 0 (NH4)2SO4 + 0 elemental S, 3) 0 urea + 0 (NH4)2SO4 + 1.8 elemental S, 4) 3 urea + 0 (NH4)2SO4 + 1.8 elemental S, 5) 0 urea + 6.6 (NH4)2SO4 + 0 elemental S. Treatments are arranged in a randomized complete block design with 5 replications. Each treatment is bordered with trees receiving like treatments. Data collection includes annual leaf samples for elemental analysis collected in July using standard leaf index tissue, annual trunk diameter measurements and the percentage of shoots bearing pistillate flowers in May, and pistillate flower cluster size. Nut samples will be harvested and kernel percentage and weight per nut determined on 40 nut samples per tree. The study will be repeated for three to five years. Data will be analyzed using a repeated measures analysis (PROC MIXED using SAS 9.4 software, SAS Institute Inc., Cary, NC, USA).Phosphorus and potassium Two studies will be conducted to meet the objectives listed above. The studies will be conducted at a commercial orchard located near Cleveland, Okla. The orchard is drip irrigated with 1 gallon per hour emitters spaced 5 feet apart about 4 feet from the tree trunk. A single drip line is located on the east side of the trees with tree rows oriented north/south. The soil is a Dennis silty clay loam. A vegetation free area 7.5 feet wide on each side of the tree is maintained with a combination of post-emergent and pre-emergent applied translocatable herbicides. Trees in both studies will receive supplemental N applied through the drip system based on the grower's judgment. Pests are controlled following Oklahoma Extension Service guidelines. Experiment 1. The study will utilize 'Kanza' trees that are 17-years-old at the beginning of the study. Treatments are 18.3 lbs/tree of 9N-24P2O5-24K2O applied 1) March [bud swell] or 2) August [full water stage]. The fertilizer will be band applied annually on the east side of the tree in the drip wetted zone. Treatments are replicated 15 times in a randomized complete block design with border trees receiving like treatments. The duration of this study will be four to five years. Experiment 2. The study will utilize 'Pawnee' trees that are 11-years-old at the beginning of the study. Fertilizer rates are 15 lbs/tree 18N-46P2O5-0K20 and 11.5 lbs/tree 0N-0P2O5-60K2O. Urea will supplement treatments where needed to provide the same N rate to all trees. Drip side and dry side in the treatment description refer to banding the fertilizer over the drip line on the east side of the tree or banding the fertilizer at the same distance from the on the opposite side of the tree where there is no drip line. The fertilizer bands will extend to the mid-point between trees. The treatments are 1) P on drip side K on dry side, 2) K on drip side P on dry side, 3) P and K on drip side, 4) P and K on dry side, 5) P on drip side, 6) K on drip side, 7) no P or K applied. Treatments are arranged in a randomized complete block design with 10 single tree replications. The study is planned for three to four years. Data and analysis. Data for both studies will include leaf samples for elemental analysis collected annually in July using standard index tissue and annual trunk diameter measurements while trees are dormant. The percentage of flower shoots will be determined in May on 30 shoots per tree along with flower cluster size. Nut samples will be harvested and kernel percentage and weight per nut determined on 40 nut samples per tree. Data from both studies will be analyzed using a repeated measures analysis (PROC MIXED using SAS 9.4 software, SAS Institute Inc., Cary, NC, USA).Kernel necrosis The study will be conducted in a commercial orchard near Madill, Okla. 'Pawnee' trees 8-years-old growing on a Madill fine sandy loam with a history of kernel necrosis will be utilized for the study. Irrigation is via microsprinklers. Trees receive broadcast application of urea at the producer's judgment. Pest control follows Oklahoma guidelines. Analysis of numerous essential and non-essential elements from sites in Oklahoma and Texas suggested that As toxicity might be associated with kernel necrosis. One method to mitigate As toxicity is application of P (Zhao et al., 2010). Treatments in this study include annual application of 1) no P, 2) 20 lb/tree 18N-46P2O5-0K2O broadcast from the trunk to the canopy drip line, or 3) 20 lb/tree 18N-46P2O5-0K2O band applied on the east side of the tree about mid-way between the trunk and drip line. Treatment arrangement is a randomized complete block design with 10 single tree replications that are bordered. The study is expected to continue for three to five years. Data will include leaf samples for elemental analysis collected annually in July using standard index tissue and annual trunk diameter measurements while trees are dormant. The percentage of flower shoots will be determined in May on 30 shoots per tree along with flower cluster size. Nut samples will be harvested and kernel percentage, weight per nut and the percentage of kernel halves with necrosis determined on 40 nut samples per tree. Data from both studies will be analyzed using a repeated measures analysis (PROC MIXED using SAS 9.4 software, SAS Institute Inc., Cary, NC, USA).Ground cover management This is a continuation of two studies that characterize tree response to selected vegetation free areas surrounding the tree in fescue or bermudagrass sods. Trees in the two studies began to crowd in 2013, and every other tree was removed. The ground covers were revised to include a mixture of bermudagrass and fescue in both areas. The two studies will be combined and tree performance monitored an additional six years. Treatments are vegetation free circles 0, 0.91, 1.83, 3.66 or 7.32 m in diameter centered on the tree are maintained vegetation-free. Treatments arrangement in the revised study are completely randomized with 9 to 14 replications per treatment. Plots are managed using standard commercial practices, and are irrigated with solid set sprinklers. Vegetation-free areas are maintained with appropriate herbicide intervention. Dependent variables include tree growth as indicated by annual trunk diameter measurements, yield, weight per nut, kernel percentage and leaf elemental concentration of selected essential elements. Data will be analyzed using a repeated measures mixed model (PROC MIXED using SAS 9.4 software, SAS Institute Inc., Cary, NC, USA).

Progress 10/01/14 to 09/30/16

Outputs
Target Audience:Pecan producers and processors in the U.S.A. and elsewhere; scientists and extension personnel working with pecans or those with interests related to the particular research project. 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?The results of each of these topics have been disseminated to scientists and extension personnel via refereed publications and presentations. In addition, results of the above studies were published in a producer oriented magazine that is widely read throughout the pecan industry. Several of these topics have been presented at producer meetings across the U.S. pecan belt. What do you plan to do during the next reporting period to accomplish the goals?I will retire August 5, 2016.

Impacts
What was accomplished under these goals? Research has demonstrated banding phosphorus and potassium over drip irrigation lines effectively increased uptake resulting in correcting shortages and improving nut quality and yields. Additional research refined refine application times and techniques to achieve the greatest return on investment and elucidate certain interactions between phosphorus and potassium affecting pecan performance characteristics. This research has been well received by producers with invited talks in Oklahoma, Texas, New Mexico, and Georgia with a recent invitation to speak at a conference in Mexico. Implementation of this research will improve production consistency and nut quality, increasing farm-gate income by millions of dollars annually. Traditionally, pecan wood for spring budding is collected while dormant using 1-year-old branches, stored refrigerated in in moisture tight bags, and then "tempered" at warm temperatures in a moist environment before it is suitable for use in the spring. Later summer and fall budding uses current season growth that is not suitable for use until the buds have matured. Thus there is about a 1.5 month window during the growing season when suitable budwood is unavailable. We found buds could be collected from 2-year-old branches throughout the growing and used that same day with better results than either traditional method. There was no need to store budwood refrigerated for long periods followed by tempering for spring budding. Additionally, use of buds from 2-year-old braches eliminated the 1.5 month window when suitable buds were not available. Several techniques and growth regulators were evaluated to improve forcing of buds in the spring following late summer or fall budding. The goal was to avoid removing the rootstock above the bud for forcing so that it could be spring budded if needed. The best combination to force the bud was removal of the bark immediately above the bud that extending one-half of the rootstock circumference and applying a combination of 5% 2,3,5-triodobenzoic acid and 0.02% 6-benzylaminopurine in a lanolin paste to the girdle. Bud forcing using this combination exceeded top removal above the bud, the traditional method of forcing. Research demonstrated that vegetation control surrounding bearing pecan trees could increase yield up to 2.5 fold and reduce alternate bearing. Maintaining the area under the tree vegetation-free 7.3 m wide resulted in the greatest yields. Certain cultivars with thin shells have a tendency to crack along the suture when dislodged from the tree or during mechanical harvest. Nuts with suture cracks are rejected by the shelling industry and have minimal value. We found that suture cracks were not associated by dislodging from the tree, but were associated with high kernel moisture and exposure to intense solar radiant energy. Up to 11% of 'Western Schley' had suture cracks rendering them unsuitable for most markets. We demonstrated that suture cracks could be reduced to about 1.5% harvesting on cloudy days or shaking nuts from the tree in the evening and harvesting the following morning before light intensity increased.

Publications

  • Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Weckler, P., C. Jones, T. Bowser, J. Hardin, N. Wang, A. Franzen, S. Mathanker, N. Maness, and M. Smith. 2015. Technologies for enhancing pecan production and processing. pp 235-243. L.J. Grauke and R. Heerema (eds.). Proc. of the First International Symposium on Pecan and Other Carya in Indigenous and Managed Systems. Acta Hort. 1070.
  • Type: Journal Articles Status: Published Year Published: 2014 Citation: Dobhal, S., G. Zhang, C. Rohla, M. W. Smith, and L.M. Ma. 2014. A simple, rapid, cost-effective and sensitive method for detection of Salmonella in environmental samples. J. Applied Microbiol. 1-10. doi: 10.1111/jam.12583.
  • Type: Journal Articles Status: Published Year Published: 2014 Citation: Smith, M.W. and B.S. Cheary. 2014. Size of the vegetation-free area surrounding pecan trees in a tall fescue sod affects production. Sci. Hort. 172:206-209.
  • Type: Journal Articles Status: Published Year Published: 2014 Citation: Smith, M.W. and W.D. Goff. 2014. Pecan nut suture splits are positively related to kernel moisture concentration and solar radiant exposure. HortTechnology 24:238-240.
  • Type: Journal Articles Status: Published Year Published: 2014 Citation: Smith, M.W. and W.D. Goff. 2014. Patch budding pecans: Girdling, tipping, age and size of budwood and rootstock for budding; girdling, 2,3,5-tridobenzoic acid (TIBA) and 6-benzylaminopurine (BAP) for bud forcing. HortTechnology 24:512-518.
  • Type: Other Status: Published Year Published: 2014 Citation: Smith, M.W. and W.D. Goff. 2014. Pecan nut suture splits are positively related to kernel moisture concentration and solar radiant exposure. Pecan Grower 24(1):8-12.
  • Type: Other Status: Published Year Published: 2014 Citation: Smith, M.W. 2014. Reducing pecan depredation. Pecan Grower 25(1):10-17.
  • Type: Other Status: Published Year Published: 2014 Citation: Bock, C.H., M.W. Htochkiss, T.B. Brenneman, K.L. Stevenson, B. Goff, M.W. Smith, L. Wells and B.W. Wood. 2014. Hedging  does it affect the severity of pecan scab? Pecan Grower 24(1):46-47, 50-52, 54, 56-58.
  • Type: Other Status: Published Year Published: 2014 Citation: Smith, M.W. 2014. Reflections on 2013. Okla. Pecan GrowersAssn. Newsletter. 54(5):1-2.
  • Type: Other Status: Published Year Published: 2014 Citation: Smith, M.W. and B.S. Cheary. 2014. Size of the vegetation-free area surrounding pecan trees in a tall fescue sod affects production. Okla. Pecan GrowersAssn. Newsletter. 54(6):6.
  • Type: Other Status: Published Year Published: 2014 Citation: Smith, M.W. and B. Goff. 2014. Pecan nut suture split. Okla. Pecan GrowersAssn. Newsletter. 54(6):7.
  • Type: Other Status: Published Year Published: 2014 Citation: Smith, M.W. 2014. 2012 Census of Agriculture. Okla. Pecan GrowersAssn. Newsletter. 54(7):5-8.
  • Type: Other Status: Published Year Published: 2015 Citation: Smith, M.W. and W.D. Goff. 2015. Patch budding pecan: girdling, tipping, age and size of budwood and rootstock for budding; girdling, 2,3,5-triodobenzoic acid (TIBA) and 6-benzylaminopurine (BAP) for bud forcing. Pecan Grower 26(1):10-26.
  • Type: Other Status: Published Year Published: 2015 Citation: Smith, M.W. 2015. Sulfur: An essential element. Okla. Pecan Growers Assn. Newsletter. 55(1):7-8.
  • Type: Other Status: Published Year Published: 2015 Citation: Smith, M.W. 2015. What will the 2015 pecan season bring? Okla. Pecan Growers Assn. Newsletter. 55(2):3.
  • Type: Other Status: Published Year Published: 2015 Citation: Smith, M.W. 2015. Baker Pecans. Okla. Pecan Growers Assn. Newsletter. 55(3):1-2.
  • Type: Other Status: Published Year Published: 2015 Citation: Montz, J. and M. Smith. 2015. Glyphosate resistant marestail (horseweed) and windmill grass. Okla. Pecan Growers Assn. Newsletter. 55(3):8-9.
  • Type: Other Status: Published Year Published: 2015 Citation: Smith, M.W. 2015. Almonds  a competitor for pecans. Okla. Pecan Growers Assn. Newsletter. 55(4):3.
  • Type: Other Status: Published Year Published: 2015 Citation: Smith, M.W. 2015. Planting and early care of pecan trees. Okla. Pecan Growers Assn. Newsletter. 55(4):4-7.
  • Type: Other Status: Published Year Published: 2015 Citation: Smith, M.W. 2015. El Ni�o still strengthening  increased scab risk. Okla. Pecan Growers Assn. Newsletter. 55(4):9-10.


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

Outputs
Target Audience:Pecan producers and processors in the U.S.A. and elsewhere; scientists and extension personnel working with pecans or those with interests related to the particular research project. 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?The results of each of these topics have been disseminated to scientists and extension personnel via refereed publications and presentations. In addition, results of the above studies were published in a producer oriented magazine that is widely read throughout the pecan industry. What do you plan to do during the next reporting period to accomplish the goals?Work will be completed on the phosphorus and potassium studies mentioned above.

Impacts
What was accomplished under these goals? Research has demonstrated banding phosphorus and potassium over drip irrigation lines effectively increased uptake resulting in correcting shortages and improving nut quality and yields. Additional research is underway to refine application times to achieve the greatest return on investment and investigate certain interactions between phosphorus and potassium affecting pecan performance characteristics. Traditionally, pecan wood for spring budding is collected while dormant using 1-year-old branches, stored refrigerated in in moisture tight bags, and then "tempered" at warm temperatures in a moist environment before it is suitable for use in the spring. Later summer and fall budding uses current season growth that is not suitable for use until the buds have matured. Thus there is about a 1.5 month window during the growing season when suitable budwood is unavailable. We found buds could be collected from 2-year-old branches throughout the growing and used that same day with better results than either traditional method. There was no need to store budwood refrigerated for long periods followed by tempering for spring budding. Additionally, use of buds from 2-year-old braches eliminated the 1.5 month window when suitable buds were not available. Several techniques and growth regulators were evaluated to improve forcing of buds in the spring following late summer or fall budding. The goal was to avoid removing the rootstock above the bud for forcing so that it could be spring budded if needed. The best combination to force the bud was removal of the bark immediately above the bud that extending one-half of the rootstock circumference and applying a combination of 5% 2,3,5-triodobenzoic acid and 0.02% 6-benzylaminopurine in a lanolin paste to the girdle. Bud forcing using this combination exceeded top removal above the bud, the traditional method of forcing.

Publications

  • Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Weckler, P., C. Jones, T. Bowser, J. Hardin, N. Wang, A. Franzen, S. Mathanker, N. Maness, and M. Smith. 2015. Technologies for enhancing pecan production and processing. pp 235-243. L.J. Grauke and R. Heerema (eds.). Proc. of the First International Symposium on Pecan and Other Carya in Indigenous and Managed Systems. Acta Hort. 1070.
  • Type: Other Status: Published Year Published: 2015 Citation: Smith, M.W. and W.D. Goff. 2015. Patch budding pecan: girdling, tipping, age and size of budwood and rootstock for budding; girdling, 2,3,5-triodobenzoic acid (TIBA) and 6-benzylaminopurine (BAP) for bud forcing. Pecan Grower 26(1):10-26.
  • Type: Other Status: Published Year Published: 2015 Citation: Smith, M.W. 2015. Sulfur: An essential element. Okla. Pecan Growers Assn. Newsletter. 55(1):7-8.
  • Type: Other Status: Published Year Published: 2015 Citation: Smith, M.W. 2015. What will the 2015 pecan season bring? Okla. Pecan Growers Assn. Newsletter. 55(2):3.
  • Type: Other Status: Published Year Published: 2015 Citation: Smith, M.W. 2015. Baker Pecans. Okla. Pecan Growers Assn. Newsletter. 55(3):1-2.
  • Type: Other Status: Published Year Published: 2015 Citation: Montz, J. and M. Smith. 2015. Glyphosate resistant marestail (horseweed) and windmill grass. Okla. Pecan Growers Assn. Newsletter. 55(3):8-9.
  • Type: Other Status: Published Year Published: 2015 Citation: Smith, M.W. 2015. Almonds  a competitor for pecans. Okla. Pecan Growers Assn. Newsletter. 55(4):3.
  • Type: Other Status: Published Year Published: 2015 Citation: Smith, M.W. 2015. Planting and early care of pecan trees. Okla. Pecan Growers Assn. Newsletter. 55(4):4-7.
  • Type: Other Status: Published Year Published: 2015 Citation: Smith, M.W. 2015. El Ni�o still strengthening  increased scab risk. Okla. Pecan Growers Assn. Newsletter. 55(4):9-10.