Bird damage, or...?

[RonObvious]

So after a great growing season thus far, we are suddenly smitten with something that is producing heavy losses, especially with our Seyval Blanc. I'm assuming this is bird damage but I'm not sure. My wife thinks it is some sort of disease or rot. The vineyard is about a mile away from our house so unfortunately we cannot be up there 24/7 to see what's going on.

As a side note, we have seen robins and other birds in the trees along the periphery - these birds are definitely doing some damage (clusters picked clean, especially near the treeline - birds going back and forth from their nests in the trees to have a snack). But the damage they produce is minor in comparison to what's going on in the rest of the vineyard.

Now as to the rest of the vineyard: We lost about 40% of our Seyval to whatever this is, and there is significant damage to the Marquette too. Each berry has a slash mark, which I assume to be a peck from a beak, but could plausibly also be a hole created by bursting from internal pressure, or some sort of bug or fungal spore or whatever. Most (but not all) of the damage occurs toward the top of the clusters, which would support the idea of birds but also perhaps sunscald or fungal spores. The affected berries smell OK - I know many fungal diseases produce peculiar funky odors but I don't smell anything like that.

Is there anything else besides bird damage that this could be?

You're probably wondering why we didn't use netting. Last year we did net about half the vinyeard and had zero damage... none in the netted side OR the un-netted side. And the netting we used was the cheap plastic stuff that tore and became tangled when we tried to remove it. So we figured we'd skip the netting this year. Big mistake!

 

[VinesnBines]

It looks like you may have spotted wing drosophila. They are a type of insect that attack ripening grapes. Nets won’t help. Spraying Surround (keolin clay) on the cluster is the preventative. Turkeys eat the whole berry. Raccoons eat part of the cluster.

 

[RonObvious]

I read about spotted wing drosophilia, but the pictures I found online of the damage don't seem to be the same. I mean, there were definitely fruitflies hanging around the vines, but my assumption was that they showed up AFTER the damage had been done and were not the cause of it.

 

[VinesnBines]

This is the damage. Not like images on the internet. I would have said botrytis since the Seyval are affected but Marquette is not so susceptible. Still may be botrytis.

 

[BigH]

IMO, your first pic looks like bird damage followed by sour rot setting in. 2nd pic looks like a different problem. I haven't seen botrytis much in my vineyard, so I will defer to others. There are two types of botrytis, with one being much worse news than the other (noble vs gray)

H

 

[tom6922]

Looks like bird damage - and you netted last year with no problems. I grow Seyval and Marquette and never had disease cause anything like this, only birds.

 

[RonObvious]

OK, thanks for the confirmation - sounds like a pretty open and shut case of birds.
I guess we learned our lesson the hard way. Next year... nets. Though I'm already not looking forward to it. Nets with VSP look relatively easy to roll up and down but we have our Marquette and other hybrids trained to a high wire. Last year we found the netting almost impossible to remove without making a mess.

 

[user 36973]

It could also be grape berry moth. Did you find many clusters had white webbing between the grapes inside the cluster? When I have bird damage, they pretty much just strip the berries off the stems. Starlings do at least.

So after a great growing season thus far, we are suddenly smitten with something that is producing heavy losses, especially with our Seyval Blanc. I'm assuming this is bird damage but I'm not sure. My wife thinks it is some sort of disease or rot. The vineyard is about a mile away from our house so unfortunately we cannot be up there 24/7 to see what's going on.

As a side note, we have seen robins and other birds in the trees along the periphery - these birds are definitely doing some damage (clusters picked clean, especially near the treeline - birds going back and forth from their nests in the trees to have a snack). But the damage they produce is minor in comparison to what's going on in the rest of the vineyard.

Now as to the rest of the vineyard: We lost about 40% of our Seyval to whatever this is, and there is significant damage to the Marquette too. Each berry has a slash mark, which I assume to be a peck from a beak, but could plausibly also be a hole created by bursting from internal pressure, or some sort of bug or fungal spore or whatever. Most (but not all) of the damage occurs toward the top of the clusters, which would support the idea of birds but also perhaps sunscald or fungal spores. The affected berries smell OK - I know many fungal diseases produce peculiar funky odors but I don't smell anything like that.

Is there anything else besides bird damage that this could be?

You're probably wondering why we didn't use netting. Last year we did net about half the vinyeard and had zero damage... none in the netted side OR the un-netted side. And the netting we used was the cheap plastic stuff that tore and became tangled when we tried to remove it. So we figured we'd skip the netting this year. Big mistake!

 

[RonObvious]

Well it's confirmed (at least to my satisfaction) that the damage is due 100% to birds. We spent most of the weekend up at the vineyard. The Seyval was ready to pick. Marquette numbers were a little shy of where we would want them to be but we can Chaptalize, so we harvested 1 row. The net I ordered arrived and we had enough to net the Petite Pearl, the 2nd row of Marquette and a couple short rows of Aromella and Arandell. Spending so much time up there we were able to observe exactly what's going on. Apparently all the damage we sustained was due to a flock of about 50 marauding robins! The flock lands in the nearby trees for a minute to survey the situation, then swoops into the vineyard like a scene from Alfred Hitchcock's The Birds. They gorge themselves for 10-15 minutes and then leave, only to come back an hour or two later. We chased them away multiple times but they are very determined! There is no doubt in my mind that they are the culprit. I would estimate that this single flock of 50-60 robins ate or destroyed AT LEAST 600 lb of grapes this year. Probably the reason that we had no problem last year is that this flock did not inhabit our neighborhood then. Lesson learned. Net, net, net, net, NET!