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Disease Detection and Losses

Effect of Anthracnose on Yield of the Tropical Forage Legume, Stylosanthes hamata. Jillian M. Lenné, Former postdoctoral research associate, University of Florida Agricultural Research Center, Fort Pierce 33450, Present address of senior author: Centro Internacional de Agricultura Tropical, CIAT, Apartado Aéreo 67-13, Cali, Colombia; R. M. Sonoda, associate professor, University of Florida Agricultural Research Center, Fort Pierce 33450. Phytopathology 72:207-209. Accepted for publication 18 May 1981. Copyright 1982 The American Phytopathological Society. DOI: 10.1094/Phyto-72-207.

The effect of anthracnose, which is caused by Colletotrichum gloeosporioides, on the yield of two selections of the tropical forage legume, Stylosanthes hamata, was measured in the field in southern Florida during 1977 to 1979. Representative plots were sprayed with benomyl or mancozeb for yield comparison with plots in which anthracnose was not controlled. Yield reduction due to anthracnose ranged 26–58% in S. hamata IRFL 7303 and 31–58% in IRFL 7413. Lesion counts were positively correlated with yield reduction percentages. There were no significant differences in yields of plots treated with different fungicides and, initially, between plots treated with fungicides and peptone. Peptone, however, lost efficacy in 1978. Seed from control, peptone-, and mancozeb-sprayed plots was 8–21% infected with C. gloeosporioides whereas seed from benomyl-sprayed plots was free of this fungus. Levels of forage loss measured during 1977 to 1979 were considerable and indicate the need for anthracnose control measures.