Effect of Storage Conditions, Age of Cyst, Root Exudates and Temperature on Larval Emergence from Cysts of Heterodera avenae and Heterodera filipjevi

After storage of 190 days, significantly more larvae emerged from the cysts of H. avenae stored at room temperature than at 6°C. But after storage of 17 months (510 days), similar number of larvae emerged at both storage temperatures. Storage of cysts with soil in cloth or polythene bags did not affect larval emergence after any of the storage period. Maximum larval emergence from cysts was obtained after third week of incubation. From gravid females, larval emergence initiated after one month at 10°C but it did not occur at room temperature. H. avenae completed one generation in a year. More (84.1%) juveniles emerged from one year old cysts of H. avenae than new season's cysts (50.7%). Initial rate of hatch was also more in old cysts. Root exudates of susceptible wheat WH147 as well as soil leachates played considerable role in stimulating larval emergence in H. avenae but not in H. filipjevi when compared with distilled water. Larval emergence in both the species took place at all the temperatures tested viz., 6, 10, 15, 20°C, and room temperature, although it was less at 20°C. Rate of emergence was more at 15°C than at any other temperature.