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Is this cutworm damage?

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RonObvious

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Numerous young shoots mysteriously disappeared from my otherwise healthy vines in the past few days. At first I thought it might be deer nibbling, but we haven't seen any deer and also, some of the shoots are partially, but not completely chewed through and I can't imagine how or why a deer would do that. Is this cutworm damage? Thanks in advance.20190609_152924893_iOS.jpg
 

treesaver

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I've also had that happen to a couple of slow growers, but it's definately not cut worms. Cut worm damage I have always had was cut off at ground level. I thought maybe a deer browsing, but have no good answers for you or me!
 

KevinL

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That is Grape Cane Girdler. I've got them as well.

https://entomology.ca.uky.edu/ef208

Grape Cane Girdler
Grape cane girdler is common in central and eastern United States. Adults girdle canes with a row of punctures, that causes canes to break off at the girdled areas. It is only a minor pest on grape, preferring Virginia creeper. Hosts include grape and Virginia creeper.

The adult is a black snout beetle about 1/8 inch long. The grub is slightly larger when full grown, and is white with a brown head and legless. It is very similar in appearance to the closely related grape cane gall maker.

Eggs are laid in late spring in a series of holes encircling the cane made by the female using its mouthparts. After eggs are laid, the female continues to make another series of punctures a few inches below the first girdle until the cane is encircled, but eggs are placed only in the holes of the first girdle. A similar girdle is made at a point higher on the cane, causing the end to break. Grubs feed in the cane pith between the girdles. After larval development is completed, pupation occurs. Adults appear in late summer, go into hibernation, and reappear in late spring.

Girdles are usually beyond the fruit clusters and do not cause significant yield loss. Look for broken off, pencil-sized canes with a grub in the pith of each broken off section, or wilted canes with a series of punctures. Pruning canes a few inches below the lower girdled area is usually sufficient control for this pest. Pruning should be done before adult emergence in late July or August.
I've found that Sevin will control them as well. My second year nearly all of my new shoots were affected until I sprayed. Then the third year I barely had any.
 

RonObvious

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Yes! That must surely be it - before I saw any responses to this thread I went up to the vineyard and sprayed Sevin, under the assumption that it was some kind of cutworm. I didn't see any worms, but I did encounter a few little black beetles. Everything is just as described in the article you shared, Kevin. I found a couple of shoots that had not yet fallen off and was able to observe the damage, but didn't know what to attribute it to until I read this. Tiny little holes girdle the shoots, which cause the shoot to shrink in on itself as if it were wearing an invisible belt that is way too tight.

Fortunately most of my vines are fine. Some sustained minor damage and 3 or 4 were almost completely defoliated. I hope the Sevin does the trick and they are able to re-grow. Thanks for the info!
 

bstnh1

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Sevin sprays used to be Carbaryl. Most are now Zeta-cypermethrin which is a less hazardous insecticide approved for vegetables and berries, including grapes. It controls many more insects than Carbaryl. It goes a long way - 4 oz. per acre! The liquid Sevin manufactured by Garden Tech that you find in most box box stores and hardware stores contains Zeta-cypermethrin.
 

Dennis Griffith

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And I like the new Sevin with Zeta-cypermethrin. It is deadly to the Japanese beetle infestations I get. Carbaryl wasn't having the effect (dead beetles) any longer, so last year I switched to this and Bingo! And I agree with KevinL. this is cane Girdler damage, and the new Sevin will work just fine for them as well. I would like to remind everyone that use of pesticides during fruit set can be bad for bees. I will sacrifice a cane or two just to safe guard the bees, but once I see the little green berries formed, I start nuking bugs again (just not bees).
 
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