Just lost 1/2 my grapes

Hello all
I just lost about half my crop, apparently from a caterpillar. About a week or so ago, everything looked fine. Now most of the leaves are damaged, and I assume they climbed in through the slots in the bottom of the bag. However, most of the fallen grapes have no damage, so I’m wondering if the caterpillars chewed out the stem, or the loss of foilage caused the grapes to drop on their own.
Last year I had some leaf damage, no bugs got in the bags and the grapes were fine. .
I weeded through all the remaining grapes, double bagged them, and put a crow bag over it. Not sure if any of them are going to make it through the season. They should be large and purple and ripe in September.
Any ideas?

https://www.youtube.com/watch?v=pOMAOCbEBIo&feature=youtu.be

While you have the bags off, might be a good time for some spray.

Bt (which is or can be organic depends on how it is made) works amazingly well on caterpillars but does not effect other insects. And of course there are stronger more broad based insecticides you could use…

I’ll try to track some down. My peach tree is next to it, with even looser fitting bags. I’m very scepticl any of those will make it, as the tree has the most insects covering it I’ve ever seen of any plant ive had.

I bagged some of my grapes last year. The bagged ones didn’t color up, plus the critters still got most of them There was no flavor to the bagged grapes I did get. Unbagged ones were much better, though few. I used brown lunch bags.

The bagging is standard here, and it works quite well. These are specially produce bags. Additionally, Commercial farmers have a large range of chemical procedures etc.
Is that the most likely explanation, the loss of leaf area caused the vine to be unable to support the amount of grapes and thus the majority of dropping?

Hi can you take a picture of these bags or tell us where to get them? Thanks!

They are clearly visible in the video posted.
Not sure where they sell them, but they are all manufactured in Japan.

What are the white bags made of? I couldn’t hear a word of the video. I can get the produce bags. Does the white bag have holes. I’m asking as I tried, cotton bags, party bags that were purple, you name it. The birds pecked right through all of the different bags I’ve used. Drives me nuts! My concords always have a fragrance to them but my Hope and Swenson’s red do not seem to have any fragrance at all yet and they are getting larger every day!

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