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ARS Home » Southeast Area » Byron, Georgia » Fruit and Tree Nut Research » Research » Research Project #439219

Research Project: Pecan Hedge-pruning: A Sustainable Management Option for the Southeastern US

Location: Fruit and Tree Nut Research

Project Number: 6042-21220-014-01-R
Project Type: Reimbursable Cooperative Agreement

Start Date: Apr 1, 2020
End Date: Mar 31, 2023

Objective:
1) Determine relative impact of tree age on horticultural and production variables, disease/insect pest prevalence, and effects on natural enemy populations. 2) Define the effect of pruning time (summer vs winter) on the variables in objective 1. 3) Perform an economic feasibility assessment of hedge-pruning pecan. 4) Share the results with growers and other stakeholders via diverse Extension and outreach programs.

Approach:
1. Assessment of production, water and nutritional status. Water potential will be determined using a pump-up pressure chamber, and soil moisture measured at 20 cm depth within the wetted zone of irrigation. Nuts will be weighed by plot for yield. A 50 nut sample will be used to determine nut size and percent kernel. Nutritional status of dormant and summer hedge pruned trees will be assessed. Leaflets will be sampled and analyzed for all macro and micro-nutrients. Temperature, light intensity and relative humidity in tree canopy will be recorded. 2. Assessment of disease infestation. 2a. Assessing scab in trees. Samples will be collected at up to 4 heights. Leaf and fruit samples will be assessed for severity of scab based on the percent area diseased by visual. The length of shoots will be measured and the number of scab lesions counted. 2b. Assessing tree limb colonization by wood rot fungi. Trees at the Marshallville site which has been hedged since 2013 will be monitored for wood rot fungi. Fifty hedge-pruned and 50 non-pruned trees will be surveyed annually by visually assessing all limbs in trees for evidence of fruiting bodies of common fungi. Species identification will be based on morphology and, if available for the fungus, by PCR diagnosis. 3. Assessment of insect pest populations, insect-related injury and beneficial insect populations. Across all studies, standard monitoring approaches for scouting insect pests will be followed. These include leaf sampling for live aphids, parasitized aphids and mites, pheromone traps for pecan nut casebearer and stink bugs and yellow sticky traps for beneficial insect. Samples will be taken bi-weekly at heights in the tree canopy. Collection of nut samples to assess for insect-related injury will be conducted. Insect injury at harvest will be assessed. 4. Assessment of belowground entomopathogens. Six soil cores will be taken 1m from the trunk and from the distance of the trunk to just inside the dripline (approximately 3m) of a hedge-pruned and non-hedge-pruned pecan tree. Samples will be pooled from within each distance. Soil will be exposed to bait insects (greater wax moth, Galleria mellonella) and Koch’s postulates used to verify presence of entomopathogenic nematodes and fungi. 5. Economic analysis, Extension and Outreach. Estimates of the relative profitability of hedge-pruned vs. non-hedge pruned systems will be evaluated by incorporating the orchard trial evidence on tree health, production measures, input costs, and market price data into a grower-level economic analysis and enterprise budget. Extension and Outreach programs will be conducted including demonstration trials, grower, industry and scientific meetings. Results will be published. Across all comparisons, treatment blocks are replicated accordingly. Data will be analyzed using standard statistical methods including analysis of variance and regression analysis.