Location: Fruit and Tree Nut ResearchTitle: Organic Approaches Pecan Management: Control of Plant Diseases
Submitted to: Pecan South
Publication Type: Trade Journal
Publication Acceptance Date: 7/25/2021
Publication Date: 8/1/2021
Citation: Shapiro Ilan, D.I., Bock, C.H. 2021. Organic Approaches Pecan Management: Control of Plant Diseases. Pecan South. 54(6)/24-33.
Technical Abstract: Pecan diseases, especially pecan scab (caused by Venturia effusa), can severely limit pecan production. Organic methods to control pecan scab are limited. The most effective approach to combat pecan scab is to plant resistant cultivars (such as Elliott, Excel, Avalon, etc.). If resistant cultivars are not available, then some curative approaches can be used to reduce pecan scab severity. Among a variety of organically labeled fungicides, the most promising treatment for reducing pecan scab was extract of the Regalia®, which based on extracts of giant knotweed, Reynoutria sachalinensis. Bordeaux mixture (a concoction including copper-sulfate and lime) also reduced pecan scab severity though results were not consistent across seasons. Other potential approaches for organic control of pecan diseases are being explored. One example includes the use of Xenorhabdus spp. and Photorhabdus spp. bacterial metabolites. In laboratory studies Xenorhabdus and Photorhabdus metabolites reduced scab sporulation and growth, and also suppressed other pecan diseases including Phytophthora and anthracnose (Glomerella cingulata). Additional research is needed to determine the field efficacy of bacterial metabolites that are effective reducing pathogen growth. Moreover, additional research is needed to optimize existing organic fungicides and expand the toolbox for organic growers to control pecan diseases in an economically efficient manner when resistant cultivars are not available.