PHENOLOGY, MONITORING, AND CONTROL DECISION COMPONENTS OF THE GRAPE BERRY MOTH (LEPIDOPTERA, TORTRICIDAE) RISK ASSESSMENT PROGRAM IN NEW-YORK

The average date and degree-day accumulation of peak egg deposition for each generation of grape berry moth, Endopiza viteana Clemens, during 1987 and 1988 are presented. Three generations were observed in 1987 but only two generations were observed in 1988. Egg deposition in 1988 was delayed on both a calendar and degree-day basis. Pheromone trap catch was an effective predictor of the temporal occurrence of grape berry moth egg deposition but was a poor indicator of the level or spatial distribution of larval damage. Action thresholds for initiating insecticide treatments of second-generation grape berry moth based on estimating population density during the 3rd wk in July were 17 and 3% damaged clusters for early- and late-harvested varieties, respectively. The operating characteristics of the currently recommended sampling procedure, consisting of two vineyard sites and 50 grape clusters inspected per site, was compared with a calculated optimal procedure. The optimal procedure required the same amount of sampling time as the currently recommended procedure and consisted of sampling five sites and 15 clusters per site. The optimal procedure performed better, but the difference between the two procedures was small. The results are discussed in the context of a risk-assessment approach for the management of the grape berry moth in New York State.