Hollow dry grapes inside cluster?

[JimInNJ]

Last year at harvest, some of my Syrah clusters, which tend to be rather compact, looked great on the outside, but hidden inside the cluster there were hollow dry shells of smallish berries that would crumble in your hand. What is up with that? Is there some known pest or disease or condition that caused it?

I wondered about grape berry moth. But I never saw any webbing that didn't have a jumping spider looking out at me. And I never saw any sting marks or damage on the outer berries.

There were some wasps, yellow jackets and flies around. But wouldn't they go after the more exposed berries?

I could understand some kind of rot getting started in there. But wouldn't it have spread?

Are there mechanical processes inside of tight clusters that could kill berries and cause them to dry out? And why do I think that whatever the answer is, it is going to be a French word?

 

[treesaver]

I've always had the same in my norton, which has very tight clusters. I will be watching this to see what the experts have to say. Speaking of which, were is Rich, haven't seen him on in quite awhile!

 

[Jack7033]

At first glance it looks like Black Rot fungus.

 

[JimInNJ]

Black Rot is one of the things I've thought about. But why would it be exclusively inside the cluster? Poor fungicide penetration perhaps. I thought Black Rot mummies would be sold, but these were more like empty shells. I've only ever seen a couple leaf spots that I identified as Black Rot, and that was the previous year.

 

[berrycrush]

could be insects eating the berry up from inside.

 

[JimInNJ]

Possibly because insecticide sprays only protected the outer berries.

 

[JimInNJ]

I caught them in the act this year. Here is part of a damaged Syrah cluster. When I started to examine it little beetles started coming out, running around and flying away. Note their size in the lower corners of the first picture. They appear to be "Sap Beetles".

- Jim

 

[Dennis Griffith]

I would say sap beetles they are. I've seen these guys on corn, with much the same effect. Or else you have a new variety of bed bugs in those grapes!