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IPM Message for Cranberry Growers: Apr 22, 2014

Apr 22, 2014

Frost Tolerance
Early Blacks, Stevens, and Ben Lear are at 20 degrees frost tolerance; Howes are at 18 as of today.
The window for putting on late water floods has closed unless your bog is in a particularly cool location and the buds are still tight and red.

Winter Moth
Growing degree days (GDD) needed for Winter Moth (WM) eggs to hatch is believed to be 177-239. Here are the GDD for locations around SE Mass, as of today:
Wareham = 207
Barnstable = 200.5
Plymouth= 222.5
Freetown= 240
Norton= 283.5

So, all areas are within the temperature accrual range of when eggs might be hatching. The timing of control sprays is important because if the newly hatched caterpillars are allowed to crawl inside the expanding buds, they are protected from any insecticide that might be applied. Scouting should be started early (ca. May 1) to catch these populations. Populations may re-occur as larvae can balloon in. Avaunt, Delegate, and Intrepidare the best choices for control of WM on cranberry.  If you have a history of WM, you may need to apply a prophylactic spray early in the season.  The Action Threshold for WM is 18 average per sweep set.