Powdery Mildew Blues

Last year my grapes were attacked by skeletonizers, this year its powdery mildew!  Ewww!  It sounds as if I'm a bad housekeeper or something.  It started with just a few leaves with white dusty patches and some with brown spots, both seen in the photo above.

The powdery mildew advanced quickly. In just a week or so big patches of leaves were curled up, brown at the edges, and nearly dead.  The literature on powdery mildew says it is not fatal to a plant, it just severely weakens it and ruins its appearance.  But I say this grapevine is on a death spiral.

I tried a popular method of slowing down the mildew growth by spraying a mixture of baking soda, liquid hand soap and water.  The treatments seemed to have little to no effect on the ravenous mildew.

My amazing garden assistant and vegan chef Amy Flemming, chopping
down mildewed grape vines.  We carefully disposed of these without
shaking and spreading the mildew spores.  We also gathered up all of
the fallen grape leaves, everything went in to our Green Barrel and NOT
the compost bin.

So I made the decision to take her down, sorry Miss Thompson Seedless.  I sacrificed you to save your neighbors, Mr. Red Flame, and your sister Ms. Thompson Seedless.

The severe pruning of the most mildewed vine seems to have helped.  The other 2 grape vines are flourishing and producing grapes!  This will be my first grape harvest.

Below is a picture of the terrible little skeletonizer caterpillars that I had last year on my grape vines.  We sprayed organic Bacillus Thuringiensis (BT for short) to eliminate the little monsters and it worked!

Western Grapeleaf Skeletonizer - Scientific name: Harrisina brillians
Photo from The World of Insects

This is what a grape leaf looks like after the skeletonizers hit - 

Next year I will be proactive and spray the new leaves as they emerge in the spring, as suggested by my friend Ruth Brown.  Maybe spray with BT one week, then a neem oil mixture the next week...?  I'm not sure, I'm just learning as I go :-).

On the other hand there is Jay Barringer of Phoenix Fruit Growers who knows exactly what he is doing!  Jay recently did 2 very informative videos on the problems you can encounter while trying to grow grapes here in the valley.  He shows the damage that Leaf Hoppers and Katydids can do to grape leaves.  Jay's incredible food forest is featured in most of his videos which are chock-full of valuable information!  Subscribe to Jay's YouTube channel Yes It Will Grow Here.