MATING TYPES OF EXSEROHILUM-TURCICUM IN ISRAEL

Fifty-one single conidial isolates of Exserohilum turcicum were collected from seven locations in Israel and three in the USA and tested for mating type and aggressiveness. Sixteen isolates mated were mating type a; 29 were mating type A; and six failed to mate with either the A or the a mating type. Isolates differed significantly in their ability to cause lesions of different sizes, and in their ability to produce conidia on the susceptible corn hybrid Jubilee. They also differed in their rate of growth on lactose casein agar. No significant difference in lesion size or conidial production was noted between mating types. Conidial production and radial growth were significantly lower for isolates with no mating capacity as compared with conidial production of defined mating types. Pseudothecia were produced after 14-16 and 21 days when mating occurred on Sorghum halepense straw or barley straw, respectively. The average number of pseudothecia produced on 10 cm(2) of straw was 17 and 8 for S. halepense and barley, respectively. Pseudothecia were not produced on corn straw.