SEASONAL HISTORY, ADULT FLIGHT ACTIVITY, AND DAMAGE OF THE OBLIQUEBANDED LEAFROLLER, CHORISTONEURA ROSACEANA (LEPIDOPTERA: TORTRICIDAE), IN FILBERT ORCHARDS

Abstract

AbstractSeasonal history, adult flight activity, and damage of the obliquebanded leafroller, Choristoneura rosaceana (Harris), on filbert were studied during a 7-year period between 1976 and 1984. Data from periodic field counts and moth catches in sex-attractant traps indicated two generations per year. The first-generation adult capture peak was generally higher than the second, except in 1978 when about an equal number of moths were trapped from both generations. A physiological time scale, using degree-days (DD), was devised for predicting emergence of obliquebanded leafroller adults. The first adults from overwintering larvae emerged at approximately 374 DD above a threshold of 10 °C starting 1 March. A total of 1172 DD were required between the first and the last adult emergence during the first generation and about 519 DD during the second generation. The obliquebanded leafroller causes both foliar and nut damage in filbert orchards of Oregon. Foliar damage was insignificant, but nut damage, caused exclusively by the first-generation larvae during June and early July, was highly destructive. Larval feeding on nuts caused staining and premature drop of infested nuts resulting in substantial yield reduction in heavily infested orchards.