New to growing grapes in Arizona? This is for you.
In April and May you will probably start seeing something like this on your grape leaves:
And if you wait very long, your entire grape vine will be filled with these “skeletonized leaves.” That is unless you are on top of it. That means knowing what to look for, when to look for it, and what to do when you find it.
When to start looking
April and May when your grapes leaf out and flowers begin to form on the vine, or when you see these flying around. They are the Western Grapeleaf Skeletonizer moths (Harrisina Brillans). They are beautiful with their iridescent coloring, but their babies will decimate your vines.
Where to look for them
Every morning as I walk around the garden I take a peak at the grape vines. Once I see the leaves come out and the flowers starting to form I keep my eye out for the beginning signs of Skeletonizer work. I also do regular inspections UNDER the leaves for eggs. I’ve noticed that the moth doesn’t usually lay eggs on new leaf growth, but on mid-size leaves. This is the best stage to catch them in because it’s easiest to control.
What to do
When you miss the opportunity to crush the eggs, you will find the larva at work, small patches at first, but they grow quickly and will move on to more and more leaves.
The best option for dealing with these pesky insects is to monitor your vines and catch them early when all you need to do is crush the eggs or remove a few infested leaves. Once they start munching through the leaves they are easy to spot, but be quick to remove the leaf.
Please note: The older catepillars have fine hairs that irritate some people’s skin and cause a rash.
If that method doesn’t work, or you can’t reach your vines, Thuricide is a good alternative. It is not a chemical, but rather a Bacillus Thuringiensis (BT) organism that feeds on the larva. It is the same thing that is in the Mosquito Dunks that I put in my Rain Barrels. It can be used up to the day of harvest.
This year my chickens are the happy recipients of these new “treats!”