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Delayed Dormant Sprays

Sunday Jan 02, 2022

Dormant sprays are important for management of a wide range of pests including European red mite, woolly apple aphid, rosy and green apple aphids, and San Jose Scale. Most of these are easily controlled using a variety of materials, but if you are using oils, remember that good coverage is essential because they work by covering the egg stage and preventing respiration.

Removing Lorsban from the Delayed Dormant Application

The first step in transitioning to no-op management of codling moth and leafrollers (LR) would be to eliminate Lorsban. Lorsban may have an important fit in IPM programs for control of woolly apple aphid (WAA) and San Jose scale (SJS), but for LR the impact of this spray is limited. The species shift from Pandemis leafroller to oblique-banded leafroller reduces the efficacy of this timing for LR control and there are several OP-alternatives that can provide very effective LR control in the post bloom period. It is very important to retain the use of Oil at delayed dormant for control of secondary pests, especially SJS and European red mite (ERM) eggs. There seems to be sufficient OP replacements for SJS, but not for WAA.

If you have persistent WAA problems, then Lorsban probably should remain in the program, at least for now.

(Jay Brunner, Keith Granger, and Mike Doerr, WSU-TFREC)

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