Occurrence of Race 2 ofExserohilum turcicumon Corn in the Central and Eastern United States

Abstract

also tested. Jordan, E. G., Perkins, J. M., Schall, R. A., and Pedersen, W. L. 1983. Occurrence of race 2 of Differences in virulence of E. turcicum Exserohilum turcicum on corn in the central and eastern United States. Plant Disease 67:1163-1165. isolates were determined using the following set of corn differentials: B37, One hundred sixty samples of northern corn leaf blight (NCLB)-infected tissue collected from B37Ht, B37Ht2, and Oh43Ht3. Corn inbreds and hybrids of Zea mays in seven states during the 1979, 1980, and 1981 growing seasons inbreds were grown in 16-cm clay pots were tested to determine which races of Exserohilum turcicum were present. Races were with one set of inbred differentials per determined by the reaction of corn inbreds B37, B37Ht, B37H2, and Oh43Ht3 after inoculation pot. NCLB lesions were cut from leaves with spore suspensions from infected tissue. Race I was virulent only on inbred B37, whereas race 2 and induced to sporulate on moist filter was virulent on both B37 and B37Ht. None of the isolates were virulent on B37Ht2 or Oh43Ht3; apd in g la te on m m). therefore, race 3 was not identified. Race 2 was identified from NCLB tissue collected in Florida, paper in glass petri dishes (1 50 X 15 mm). Illinois, Indiana, Iowa, Pennsylvania, Minnesota, and New York. Race 2 was widespread in Illinois A spore suspension of each isolate was (53 counties) and Indiana (24 counties). prepared by washing conidia from infected leaf tissue and adjusting the concentration to about 20,000 spores per Northern corn leaf blight (NCLB), year at several locations in Ohio (11). The milliliter. Each spore suspension was caused by Exserohilum turcicum (Pass.) purpose of this paper is to report the sprayed on two replicates (two or three Leonard & Suggs (imperfect state of distribution of race 2 in Illinois and plants per replicate) of the inbred Setosphaeria turcica (Luttrell) Leonard Indiana and its occurrence in other states. differentials. Inoculations were made & Suggs), was first observed by Passerini