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United States Department of Agriculture

Agricultural Research Service

Title: Development of Standardized Techniques for Screening Natural Product Fungicides

item Wedge, David
item Smith, Barbara

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: April 6, 2003
Publication Date: June 1, 2004
Citation: Curry, K.J., Wedge, D.E., Smith, B.J. 2004. Development of standardized techniques for screening natural product fungicides. Phytopathology. 94:S167

Technical Abstract: We developed two standardized procedures that improve the reliability of in vitro fungicide testing using strains of Colletotrichum and Botrytis. They required different incubation temperatures, but all were grown under cool-white fluorescent lights with a 12 h photoperiod. Fungi were grown on Roswell Park Memorial Institute medium 1640. (1) We developed a protocol for standardizing spore germination times. A concentration of 105 conidia/ml, harvested after10 to 14 days, was optimal. Higher concentrations inhibited germination. We washed conidia three times in sterile water, thus significantly reducing germination time. (2) We developed a leaf-clearing technique to assess reproducible germination conditions using detached strawberry leaves. Small leaf pieces were placed overnight in a solution of 1:2 absolute ethanol:glacial acetic acid, stained with 0.05% acid fuchsin for two minutes, and water rinsed. The leaves were clear, viable conidia were bright red, and nonviable conidia were clear.

Last Modified: 4/18/2015
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