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Disease Control and Pest Management

Effect of Furfural on the In Vitro Germination of Peronosclerospora sorghi Oospores. R. C. French, Plant physiologist, Plant Disease Research Laboratory, AR-SEA, U.S. Department of Agriculture, P.O. Box 1209, Frederick, MD 21701; C. G. Schmitt, research plant pathologist, Plant Disease Research Laboratory, AR-SEA, U.S. Department of Agriculture, P.O. Box 1209, Frederick, MD 21701. Phytopathology 70:877-880. Accepted for publication 2 March 1980. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1980. DOI: 10.1094/Phyto-70-877.

Methods of inducing germination and controlling contamination in oospores of Peronosclerospora sorghi were evaluated. Oospores centrifuged from autolysed sorghum leaf tissue had fewer contaminants than did those sieved from ground, dry tissue. Furfural, at 50–100 μl/L, was effective in stimulating germination and/or suppressing contamination. In the presence of furfural, dried spores commenced germination after 3 days on agar, reached a maximum at about 5 days, but were scarcely observable after 9 days at room temperature (~25 C) because germ tubes had disintegrated or were indistinguishable from mycelia of contaminants. Washed oospores (from autolysed leaves) that were not allowed to dry sometimes germinated within 2 days. Germination occurred at 16–30 C and was most rapid (3–5 days) at 26–28 C. Great variability in percent germination was attributed to the variability in contamination and in the proportion of mature viable oospores produced in the leaf tissue.