Poster Session: Biology of Pathogens - Mycology

30-P

Host range evaluation of Cercospora sojina, causal agent of frogeye leaf spot of soybean.
G. ZHANG (1), U. Reuter-Carlson (1), D. K. Pedersen (1), C. A. Bradley (1)
(1) University of Illinois, Urbana, IL, U.S.A.

Cercospora sojina causes frogeye leaf spot (FLS) of soybean, but little has been published on its host range. In a greenhouse trial, 20 legume species, 10 weedy plants, cotton, and sweet corn were inoculated with C. sojina and evaluated for infection by observing symptoms, by using microscopy, and by isolation onto culture media. Typical FLS symptoms appeared on the legumes mung bean, adzuki bean, winged bean, guar bean, snap pea, winged pea, pigeon pea, sunn hemp, and red clover, and on the weeds morning glory and poison hemlock. Symptoms atypical of FLS appeared on the legumes lima bean, cowpea, peanut, hairy vetch, fava bean, Chinese mosaic yard long bean, scarlet runner bean, lentil, and snap bean, on the weeds common ragweed, common waterhemp, palmer amaranth, morning glory, smooth pigweed, velvetleaf, common lambsquarters, and giant ragweed, and on cotton. No symptoms appeared on chickpea, alfalfa, horseweed, redroot pigweed and sweet corn. Inoculated leaf surfaces were sterilized with a 10% NaOCl solution, and placed on culture media for C. sojina isolation. Cultures resembling C. sojina were evaluated for morphological characters and verified as C. sojina using ITS primer sequence. Out of all potential hosts tested, results of C. sojina and microscopy isolations indicated that only chickpea and sweet corn were nonhosts.