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ARS Home » Southeast Area » Byron, Georgia » Fruit and Tree Nut Research » Research » Publications at this Location » Publication #301417
Title: Identification of a naturally produced antifungal compound with activity against pecan scab

Author
item Bock, Clive
item Shapiro Ilan, David
item Wedge, David
item Cantrell, Charles

Submitted to: Pecan Grower
Publication Type: Trade Journal
Publication Acceptance Date: 12/10/2013
Publication Date: 3/1/2014
Citation: Bock, C.H., Shapiro Ilan, D.I., Wedge, D.E., Cantrell, C.L. 2014. Identification of a naturally produced antifungal compound with activity against pecan scab. Pecan Grower. 25:52-60.

Interpretive Summary: Pecan scab limits the productivity of pecan in the southeastern United States. Alternatives to conventional fungicides are needed, and ideally should be biorational, of low environmental risk with a reduced risk for fungicide resistance. Extracts of a bacterial symbiont (Photorhabdus luminescens) from an entomopathogenic nematode were investigated using bioactivity-directed fractionation to identify the constituent(s) responsible for the activity. One of the metabolites was purified and identified as trans-cinnamic acid (TCA). In-vitro tests confirmed toxicity of TCA to Colletotrichum spp. (cause of anthracnose) and to F. effusum (cause of pecan scab). Naturally occurring anti-microbial products might offer a future alternative for control of pecan scab. Much additional research is warranted to determine the potential to use TCA as a suppressive agent for pecan scab and/or other diseases.

Technical Abstract: Pecan scab limits the productivity of pecan in the southeastern United States. Alternatives to conventional fungicides are needed, and ideally should be biorational, of low environmental risk with a reduced risk for fungicide resistance. Extracts of a bacterial symbiont (Photorhabdus luminescens) from an entomopathogenic nematode were investigated using bioactivity-directed fractionation to identify the constituent(s) responsible for the activity. One of the metabolites was purified and identified as trans-cinnamic acid (TCA). Laboratory tests confirmed toxicity of TCA to fungal species causing anthracnose (Colletotrichum spp) at 10 and 100 µg mL-1 using further bioassays. The activity of TCA was also tested in the laboratory against pecan scab (Fusicladium effusum), and showed toxicity at concentrations of 148-200+ µg mL-1. Naturally occurring anti-microbial products might offer a future alternative for control of pecan scab. Much additional research is warranted to determine the potential to use TCA as a suppressive agent for pecan scab and/or other diseases.