This dry spell has been wonderful and I hope it continues. All this warm weather has pushed the trees and pushed apple ascospore maturity. Currently, approximately 40% of the overwintering spores are mature and ready to be released during the next rainy period. The next wetting period will most likely be the most important wetting period of the primary scab season. What would be ideal is if we get a soaking rain and then the weather dries up – so the spores are released, but die before the spores can cause an infection. You certainly can’t depend on this so you need to have your trees well protected with a fungicide before the next rain.
We still have had only one infection period this season. That infection period occurred April 27-28. Scab lesions from this infection period are expected to begin appearing around May 10th.
I am a bit concerned about fire blight on apple trees in Providence County – especially if an orchard experienced fire blight over the past 2 years (or within 1 mile of an orchard with fire blight.) We haven’t had much heat in Rhode Island in the past, but then again, we don’t usually get temperatures in the 80’s during bloom. (According to two models, Cougar Blight and Mayrblyt, as of 5/9 it looks less likely that we’ll have a fire blight infection on May 11, compared to yesterday’s prediction. The daytime temperature has not reached forecasted highs.)
If you did have fire blight over the past 2 years, it is probably warranted to apply a Streptomyecin spray on Thursday, May 10th. If your orchard has not experience fire blight in the past, hopefully your trees will be fine!
Bloom is not the time to apply insecticides. Only orchards in colder areas where no blooms have opened can consider applying insecticides. Be prepared to apply an insecticide at petal fall, when 95% of the petals have fallen. Use Imidan or Avaunt.
At the twilight meeting at Jaswells Farm on May 17 at 5:30, we will have available the New England Fruit Pest Management Guides. These guides include pest control recommendations for apples, pears, and stone fruits. The guides will cost $30 at the twilight meeting, and $35 if I need to mail it to you. Once you buy the guide, you will also be given a password so that you can access the guide on-line.
Next message will be recorded 5/15/07 and emailed 5/16/07.