Time to prepare for fruitworm activity in blueberries
Cherry fruitworms and cranberry fruitworms are two early-season moth pests of blueberries in eastern North America. Both species have one generation per year and the female moths lay eggs during and after bloom, with cherry fruitworm activity being seven to 10 days earlier than cranberry fruitworm. The larvae of both species develop inside berries through the period of fruit development, and left unchecked these insects can infest 50 to 75 percent of clusters in areas of high populations. This causes risk of reduced yield and load rejection due to a very low tolerance for insects in fruit destined for the fresh or processing markets.
Effective management of fruitworms requires understanding how to monitor and scout for these insects, knowledge of their emergence and egglaying, and the performance of the available control options. Combining these approaches into an integrated pest management (IPM) program can help ensure that fruitworms do not cause economic losses. This article explains how to use the MSU degree day model for fruitworm management, and we report on some recent trials to test the performance of IPM programs that tested the degree day model and alternatives to Guthion (which is being phased out by September 2012). Blueberry growers have many alternatives available and should be testing alternative programs on their farms to be prepared for this change.