Current Status of Soybean Stem Canker in Florida. R. C. Ploetz, North Florida Research and Education Center, Route 3, Box 4370, Quincy 32351. R. K. Sprenkel, and F. M. Shokes, North Florida Research and Education Center, Route 3, Box 4370, Quincy 32351. Plant Dis. 70:600-602. Accepted for publication 2 February 1986. Copyright 1986 The American Phytopathological Society. DOI: 10.1094/PD-70-600.

Soybean-growing areas in Florida were surveyed in 1983, 1984, and 1985 for soybean stem canker. Incidence of the disease was much lower in 1984 and 1985 than in 1983. As many as 81% of the fields in a given county in 1983 contained diseased plants, but the highest comparable proportions in 1984 and 1985 were 8 and 2%, respectively. An abrupt reduction in the use of susceptible cultivars was observed during the 1984 and 1985 seasons in counties where the disease was perceived as a threat to soybean production after 1983 (counties with severe stem canker in 1983 or in adjacent counties). Whereas about 50% of the seed sold in these counties in 1983 were susceptible to stem canker, generally less than 10% of the seed sold in the same counties in 1984 and 1985 were of susceptible cultivars. In contrast, in counties not affected by stem canker in 1983 about 50% of the seed sold during 1984 and 1985 were of susceptible cultivars.

Keyword(s): Diaporthe phaseolorum var. caulivora, southern D. phaseolorum.