Ethephon and NAA Facilitate Early Harvesting of Pecans

in Journal of the American Society for Horticultural Science
Author: Bruce W. Wood1
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  • 1 Agricultural Research Service, U.S. Department of Agriculture, Southeastern Fruit and Tree Nut Research Laboratory, P.O. Box 87, Byron, GA 31008


In an attempt to solve the problems of nonuniform and delayed shuck dehiscense of pecan [Carya illinoensis (Wangenh.) C. Koch], ethephon and NAA were evaluated for their efficacy as harvest-aid treatments. A 3-year study under commercial-like orchard conditions using 75-year-old ‘Stuart’ trees resulted in a spray mixture of 9 mm ethephon and 1.5 or 3.0 mm NAA, or just 9 mm ethephon alone, accelerating shuck dehiscence by 1 to 2 weeks relative to that of the nontreated control. While all three treatments induced some degree of leaflet abscission, the two treatments employing the NAA and ethephon combination induced only about one-fourth (21% vs. 75%) as much leaflet abscission as when ethephon was used alone. However, this level of leaflet abscission (21%), plus an associated 50% drop in net photosynthesis for several days post-treatment, was sufficient to reduce in-shell nut yields in subsequent years. This appears to preclude commercial acceptability of such treatments for pecan. Chemical names used: (2-chloroethyl)phosphonic acid (ethephon), 1-napthaleneacetic acid (NAA).

Contributor Notes

Research Horticulturist.

Received for publication 18 Dec. 1987. Trade names are used in this publication to provide specific information. Mention of a trade name does not constitute a guarantee or endorsement by the USDA over other products. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper therefore must be hereby marked advertisement solely to indicate this fact.