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United States Department of Agriculture

Agricultural Research Service

Related Topics

Research Project: INCREASING FRUIT RETENTION AND OVERCOMING LEAF SCORCH AND SCAB OF PECAN TREES

Location: Fruit and Nut Research

2011 Annual Report


1a.Objectives (from AD-416)
This collaboration seeks to address alternate bearing associated crop losses by evaluating efficacy of two orchard management strategies for improving commercial-scale pecan production. These include increasing fruit-set of pecan trees and reducing crop loss and alternate bearing caused by leaf scorch.


1b.Approach (from AD-416)
A registered growth regulator (ReTain) is used in a ‘Desirable’ orchard to prevent excessive fruit-drop. Systemic acquired resistance inducers and micronutrients are used in a ‘Cape Fear’ orchard to overcome canopy and yield loss to leaf scorch and scab. The fruit retention study will use 'Desirable' trees sprayed post-pollination to retain fruit that otherwise drop during the June-drop phase of fruit development. Treatments will be untreated and treated (ReTain). The growth regulator is provided at no charge by Valent BioScience, Memphis, TN. Treatments will be replicated a minimum of 6 times, in large block rows, with yield and quality being assessed in the autumn for treatment effects. Return bloom will be assessed the following spring. The second study will evaluate several treatments (SAR inducers, micronutrients, and combinations) applied to single trees, involving about 50 trees. The study might need to be repeated for an additional one or two years.


3.Progress Report

This research relates to inhouse objective 1: Provide improved horticultural tools for stabilizing pecan nut yields in alternate bearing pecan trees and orchards.

A commercialized natural growth regulator product was found to possess potential for reducing nut-drop of certain pecan cultivars, thus increasing yield in "off" crop-load years. Research results indicate that timely treatment of canopies with an ethylene inhibitor (i.e., AVG or ReTain) reduces fruit-drop in certain crop years, but not in all years, thus, leading to another year’s study of usage in a heavy “on” crop year.

Progress was monitored via on-site visits and on-site data collection.


Last Modified: 7/22/2014
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