OFM Degree Days and Optimal Spray Timing, 6.25.20

As of June 25, the degree day model for predicting hatch of 1st brood codling moth eggs shows 97% hatch for Winchester and 100% hatch for Batesville and Red Hill in central Virginia. Recent research by Dr. Jim Walgenbach from North Carolina showed that the traditional codling moth developmental model from Michigan State was predicting an earlier flight of second generation adults in our region than was reflected by pheromone traps. Therefore, recommendations for timing sprays against 2nd brood codling moth larvae were revised by adding 200 degree days to the timings recommended by the Michigan model, and this has proved to perform well. I will resume posting codling moth degree day accumulations for our area as we get nearer to the critical timings for 2nd brood. Similarly, I will resume posting degree days for oriental fruit moth when we approach those critical timings for 3rd brood.

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