Disease Note.

Occurrence of Target Leaf Spot (Bipolaris sorghicola) on Sorghum in Mississippi. N. Zummo, USDA-ARS, Crop Science Research Laboratory, Mississippi State, MS 39762. L. M. Gourley, Department of Agronomy, Mississippi State University, Mississippi State 39762. Plant Dis. 71:1045. Accepted for publication 14 July 1987. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/PD-71-1045B.

Target leaf spot of sorghum (Sorghum bicolor (L.) Moench) caused by Bipolaris sorghicola (Lefebvre & Sherwin) Shoem. was observed in the sorghum test field at Mississippi State, Mississippi, during the summer of 1986. The lesions of target leaf spot resembled those of gray leaf spot incited by Cercospora sorghi Ell. & Ev. Target leaf spot on sorghum in the field can often be distinguished from gray leaf spot by the rather distinct circular center in each target leaf spot lesion. Greenhouse-grown plants of 11 sorghum lines showing target leaf spot in the field and one line that remained free from symptoms were spray-inoculated to runoff with a spore suspension (1,000 spores / ml) of B. sorghicola obtained from oatmeal agar cultures isolated from field infected sorghum plants. Inoculated plants were kept at 100% RH for 12 hr before being returned to the greenhouse bench and were evaluated after 5 days. All sorghum lines that showed target leaf spot in the field showed typical symptoms in the greenhouse. The sorghum line that remained free from symptoms in the field remained free from symptoms when inoculated in the greenhouse. This is the first report of the disease in Mississippi.