The Use of Pheromone Traps for Leafroller Action Thresholds in Pipfruit

In orchards using New Zealand Integrated Fruit Production for pipfruit (NZIFP-P), the decision to treat for leafroller (Lepidoptera: Tortricidae) results from sampling of 200 fruit clusters or 200 shoots. This required a large time commitment by the grower, was subject to misidentification and was a poor predictor of damage at harvest. In 1996-97, cumulative trap catch of Epiphyas postvittana (LBAM) within NZIFP-P research plots was found to be highly correlated with damage at harvest and a cumulative catch of 30 moths after 15 December was established as a tentative threshold. Insecticides were to be applied at least 21 days apart during periods of high trap catches. In 1997-98, this threshold was successfully used by 300 growers and using their trap data, the effect of increasing the threshold to 50 was examined. The 50 moth threshold is not appropriate in Otago, but in northern regions shows some potential and requires further evaluation.