Assessment of Urediniospore Germination of Puccinia striiformis at Various Temperatures on Agar and Detached Leaves of Wheat

The percentage of urediniospore germination of two isolates of yellow rust {Puccinia striiformis f. sp. tritici) namely, WYR 69/10 |Race 104E 137(1)] and isolate WYR 79/4|Race 41E 139 (4)], was studied at various temperatues between 5-20°C on agar and the adaxial surface of detached leaves on a layer of benzimidazole agar. Four replicates for five temperature treatments were arranged as a preliminary investigation to find the most appropriate temperature for the subsequent comparison of spore germination on the host material under investigation. Mean percentage values were analysed separately and the levels of urediniospore germination at different temperatures were compared using analysis of variance and Student- Newman-Keuls techniques. Spore germination of both isolates was high over the temperature range 5-10°C, but dropped significantly at 15-20°C . At the cooler temperatures 5° , 7.5° and 10°C , isolate WYR 69/10 consistently germinated at a higher level than isolate WYR 79/4 , whereas at 20°C, the latter isolate gave the highest figures. This observation indicates that both isolates germinated most effectively at 10°C on agar and detached leaves