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Title: Evaluation of CAY-1, an Experimental, Natural Fungicide for Control of Strawberry Pathogens

Author
item ABRIL, MARITZA - UNIV. OF SOUTHERN MS
item CURRY, KENNETH - UNIV. OF SOUTHERN MS
item Smith, Barbara
item De Lucca Ii, Anthony
item Boue, Stephen
item Wedge, David

Submitted to: Acta Horticulturae
Publication Type: Proceedings
Publication Acceptance Date: 3/15/2008
Publication Date: 8/31/2009
Citation: Abril, M., Curry, K.J., Smith, B.J., De Lucca Ii, A.J., Boue, S.M., Wedge, D.E. 2009. Evaluation of CAY-1, an Experimental, Natural Fungicide for Control of Strawberry Pathogens. Acta Horticulturae. 842:295-298.

Interpretive Summary: CAY-1 a saponin isolated from Capsicum frutescens that was tested as a potential fungicide for control of strawberry anthracnose. In an in vitro dose-response dilution-broth assay, CAY-1 and the commercial fungicide captan caused at least 85% growth inhibition of the fungal pathogens, Colletotrichum acutatum, C. fragariae, and C. gloeosporioides when tested at 3.0 µM. CAY-1 and the azoxystrobin control prevented anthracnose leaf lesions in a detached leaf assay when applied prior to inoculation with spores of C. fragariae, but neither prevented lesion development when applied 24 hr after inoculation. Efficacy of two concentrations of CAY-1 and azoxystrobin was compared to no fungicide treatment in field trials for control of Botrytis gray mold, anthracnose fruit rot, stem end rot, and foliar diseases of strawberry. Even though CAY-1 strongly reduced the growth of several fungal pathogens in laboratory assays and prevented anthracnose development in detached leaf assays, it did not control foliar or fruit rot diseases of strawberry in field trials.

Technical Abstract: CAY-1 is an experimental, natural product being tested as a potential fungicide. It is a saponin isolated from Capsicum frutescens that interacts with membrane sterols to cause leakage of cell components and ultimately cell death in a variety of fungi. In an in vitro dose-response dilution-broth assay, CAY-1 and the commercial fungicide captan caused at least 85% growth inhibition of the fungal pathogens, Colletotrichum acutatum, C. fragariae, and C. gloeosporioides when tested at 3.0 µM. Efficacy of CAY-1 against strawberry anthracnose was compared to the commercial fungicide azoxystrobin using an in planta detached leaf assay on Fragaria x ananassa. Both fungicides prevented anthracnose leaf lesions when applied prior to inoculation with spores of C. fragariae, but neither prevented lesion development when applied 24 hr after inoculation. No phytotoxicity was observed during detached leaf assays. Efficacy of two concentrations of CAY-1 and azoxystrobin was compared to no fungicide treatment in field trials for control of Botrytis gray mold, anthracnose fruit rot, stem end rot, and foliar diseases of strawberry. Significant differences among fungicide treatments occurred in marketable yield, diseased yield, and size of berries. Plots treated with CAY-1 had marketable yields lower than the commercial fungicide and comparable to the untreated plots. Anthracnose was the most prevalent fruit rot in these trails. The number of anthracnose infected berries and the total number of berries with any fruit rot symptoms were as high on the two CAY-1 treated plants as on the untreated plants and higher than on plants treated with the commercial fungicide, azoxystrobin. Even though CAY-1 strongly reduced the growth of several fungal pathogens in laboratory assays and prevented anthracnose development in detached leaf assays, it did not control foliar or fruit rot diseases of strawberry in field trials. Improvements in the formulation of CAY-1 might improve its field performance.