EFFECT OF STORAGE ON THE SURVIVAL AND BIOCONTROL ACTIVITY OF PYTHIUM-OLIGANDRUM IN PELLETED SUGAR-BEET SEED

Seeds of sugar beet were pelleted with oospores of Pythium oligandrum and stored for 6 years at 8 +/- 20 degrees C. Mycelium of P. oligandru m grew from pelleted seed when plated on cornmeal agar (CMA) within 48 h from 100% of seeds stored for 0, 2 and 4 years, and from 93% of see ds stored for 6 years The germination of oospores removed from pellete d seed immediately after pelleting was 30% on CMA after 18 h of incuba tion, but storage gradually reduced germination to only 16% after 48 h of incubation for oospores removed from seed stored for 6 years. The biocontrol activity of P. oligandrum-pelleted seed was also tested aft er 6 years of storage in mixes of soil naturally infested with Pythium spp. and Aphanomyces cochlioides, and sand. P, oligandrum-pelleted se ed had no effect in reducing damping-off due to the combined effect of Pythium spp. and A. cochlioides in 5 and 1% (v/v) soil-sand mixtures. However, in the 1% (v/v) soil-sand mixture, P. oligandrum significant ly reduced Pythium spp.-induced damping-off from 33 to 26%.