EVALUATION OF OATS FOR RESISTANCE TO LOOSE SMUT

The percentage of loose smut (Ustilago avenae) infected plants in oat (Avena sativa) cultivars and breeding lines was determined after kerne ls were inoculated in a vacuum with water suspensions of teliospores. Fifty-two oat cultivars were evaluated between 1978 and 1990; 14 were resistant, six were moderately resistant, and 32 were susceptible. Man y advanced breeding lines were also resistant. Factors that might affe ct the incidence of smut infection in evaluation trials were studied w ith cultivars Moore (moderately resistant), Ogle (susceptible), and St arter (resistant). One to three exposures in the vacuum during the ino culation procedure did not greatly affect the incidence of loose smut in the cultivars. As inoculum concentration decreased, the incidence o f loose smut decreased, but incidence was not generally affected by st oring inoculated seed for 6 wk before planting. In these tests, Starte r consistently had the least infection, and Ogle the most; Moore was i ntermediate. Removal of the lemma and the palea prior to inoculation i ncreased the incidence of smut 10-20%, depending on the cultivar.