I Feel Really Bad for Sue and Her Grapes Frying After Dipel

Q. I e-mailed you awhile ago about issues with my grapes.  The GOOD news is, I had been pruning them totally wrong.  Following cane pruning instructions off of YouTube, in February I had more vines and grape clusters than since we moved in.  The bad news is that I was so excited about the grapes and worried about the pests (big black things and skeletonizers?) I followed your instructions and used Dipel Dust (just once) for prevention. 

Everything was fantastic until two weeks ago.  I had beautiful green grape leaves and so many clusters of grapes and on the turn of a dime…everything fried and I mean I hardly have a leaf and the clusters are practically burnt raisins now if anything.  I am so sad.  What did I do wrong do you think?  My intuition is telling me that the Dipel, like other pesticides I have tried, burn the leaves in the sun when it gets into the high 90’s?  Ugh, I am so bummed.  Anyhow, let me know what you think.  Thank you so much.

Sue

A. I rather doubt it was the Dipel if you applied according to the label. I usually use the liquid form of Dipel or Thuricide when I use it. Or I will use Spinosad instead which does the same thing but hits a few more insects including the skeletonizers.

This is Dipel DF or dry flowable and intended to be
mixed with water, not applied as a dust. Please read
the label before applying any pesticide.

Regardless you still would want to apply any pesticide even if it is organic like Dipel, in the early morning hours or late afternoon when it is no longer hot outside. Dipel powder is hard to distribute evenly over a grape vine while the liquid form is much easier to spray as is spinosad.

We use both products at the orchard and have had no problems with it when sprayed this time of year even around 8 or 9 am. I would next time though stick with a liquid product. It will give you better coverage over the leaf, both top and bottom, and is easier to apply. You should not be using the Dipel dust. Make sure you did not apply the Dipel DF as a dust. It is meant to be mixed in water and sprayed on.

Has anyone else had this problem with Dipel on grapes? I would love to know. Please check the label before using just in case.