Degree-day phenology of San Jose scale, Quadraspidiotus perniciosus Comstock and assessment of its predator, Chilocorus bijugus Mulsant in Kashmir orchard ecosystem.
The San Jose scale overwintered in black cap stage in Kashmir apple orchards. The overwintered nymphs started development at silver-tip stage of apple growth in the first week of March. The spring male emergence which resulted from overwintering black caps began at 285 degree-days (DD) at a base of 51°F (10.5°C) and occurred at completion of petal fall of Red Delicious. This could be used as “biofix” for timing the succeeding phenological events of San Jose scale. First generation crawlers emerged at 534 DD in the last week of May and peaked within 10 days. The males of summer generation were observed at 1277 DD and the second generation crawlers emerged beyond 1357 DD. The winged males were again observed at 2529 DD followed by the emergence of partial third generation crawlers past 2740 DD. The common ladybird beetle, Chilocorus bijugus Muls. was observed to be an effective and predominant predator of San Jose scale which passed three generations along with its host. It was also observed that the development of this predator corresponded to the development of San Jose scale and has got well established in the orchard ecosystem.