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Grape Problem

Posted by pokerguard AZ (My Page) on
Sun, May 10, 09 at 15:54

Wondering if anyone can tell me what they think is wrong with my Thompson Seedless.

It came out strong in the spring, with new growth, and even flowered for grapes... but then, all of a sudden, all the leaves have started doing what is shown in the pics.

It is getting water just fine. Is there a fungus or something perhaps?

Pictures can be seen here:



Follow-Up Postings:

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RE: Grape Problem

EEeeeek!! Grape leaf skeletonizers!! You need - quickly - to treat your plants with Thuricide. The skeletonizers are actually little catepillars - about an inch long that are yellow and black. Some people pick them off, but be careful not to rub your eyes or nose as they how some kind of stickery stuff on them that can be very irritating. Move on this as soon as you can as they can kill a plant within a few days.


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RE: Grape Problem

I dought it is an insect problem. A close up photo would more helpful but from these photos, I would say the problem is Black Rot mainly because the fruit is affected. Google Black Rot or contact your local Cooperative Extension Service for specific recommendations.


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RE: Grape Problem

Looks like skeletonizers to me too. The leaf veins are intact. Black rot attacks the stems too.


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RE: Grape Problem

It appears it is the skeletonizers.... see pictures. so, I haven't been able to find the BT, Dipel, or Thuricide at home depot or loewes. Anyone know where I can find it?

I just picked about 100 of these off my 2nd grape plant. My first one is just a skeleton at the moment, but new leaves are sprouting.



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RE: Grape Problem

I've always found BT at the Blue or Orange big box stores. One brand is Green Light. You may want to try calling a garden center or nursery in your area. Someone has to have one or the other. I like BT because it doesn't affect most of the bennneficial insects.


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RE: Grape Problem

I have a small vineyard myself and have been told these skeletonizers were the worst of the few things i have to worry about in my area, but i've never actually seen them. Thank you to every one who participated in this thread. Seeing pictures of an affected vine and the caterpillars themselves was very educational. btw, sorry about your vine:( the person who told me about these guys said the best thing that worked for her was just catching and smashing them in her fingers. she also said thay are sticky and to avoid the eyes/ face because it can cause irritation. thanks again!


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RE: Grape Problem

BT is an acronym for Bacillis thuringiensis, a bacteria that only affects caterpillars. Applied to leaves when the caterpillars ingest it it disrupts digestion and they basically starve. The best thing about it is that no other insects/mammals will be affected by the product - only caterpillars.

Motown gave you good advice - the stinging hairs on the caterpillars can cause skin rashes. Be careful.
Here is a link to information and photos from the University of California at Davis.

Here is a link that might be useful: Grape Leaf Skeletonizer


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RE: Grape Problem

Hi!
I live in Mesa and have these too- I dont really know what I am doing, my grape vine is only 2 years old, but I found thuricide at a nursery -Harpers- that was on gilbert road and McKellips. It was ten dollars for a bottle that will last me a decade. I read that you spray it and the bugs dont die, they just stop eating. I have sprayed a couple times and still have problems but they might still be hatching or something. The spray only lasts 24 hours once diluted, so just use a small spraybottle full. Good luck to you!


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RE: Grape Problem

sweet link! does anyone know if they are still dangerous to grape vines once in moth form? or will they just leave.


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RE: Grape Problem

I've gotten Thuricide at A&P Nursery.


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RE: Grape Problem

I picked up some spinosad from Whitfills, in liquid form so I can spray it on the leaves. They had Dipel as well (BT), but it was powder form and seemed more of a pain to target on leaves.

Here's a picture after I found one of the colorful purple moths on a brand new leaf from my recovering skeletonized (completely) grape plant - eggs?:


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RE: Grape Problem

For those organic gardeners out there, Thuricide contains a petroleum product and is not an OMRI approved product. Just plain old BT is OMRI approved but should only be used when absolutely necessary (we are seeing BT immune caterpillars thanks to overuse & BT seeds from Monsanto). BT is the best product for skeletonizers...and that's what you have for sure. Be aware that BT breaks down rapidly in sunlight...so apply it early in the day or evening and reapply every 48 hours until the problem subsides. The caterpillars have to eat the product in order to have it kill them (actually makes them stop eating). It can take 48-72 hours to see the caterpillars begin to die. You will probably have 2 or 3 outbreaks before autumn comes. Watch for them!


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RE: Grape Problem

Thanks for the heads up on watching out for them. I had actually found a university study conducted in CA, and they had found that Spinosad (sp?)actually worked better than BT in their field test of 5 products.


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RE: Grape Problem

Help! I have the skeletonizers. They are four different size worms (yellow and purple). I have been told to spray both vines with Sevin. Will Sevin kill the worms? Is the fruit safe to eat after using Sevin? The worms appear to been eating the vines from the ground up because I still have a lot of leaves on the vines along with a large crop of grapes. Is this fruit going to mature or die? What other plants are in danger of getting this worm. I have a back yard garden and a few fruit trees? Help, please.


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RE: Grape Problem

The skeleteonizers only target grape vines. The adult is a small blue-black moth although it looks similar to a wasp. The eggs are laid on the underneath sides of the leaves so they are hard to spot until the caterpillars hatch and begin munching.

The active ingredient in Sevin is Carbaryl. Carbaryl is moderately to very toxic. It can produce adverse effects in humans by skin contact, inhalation, or ingestion. The symptoms of acute toxicity are typical of the other carbamates. Direct contact of the skin or eyes with moderate levels of this pesticide can cause burns. Inhalation or ingestion of very large amounts can be toxic to the nervous and respiratory systems resulting in nausea, stomach cramps, diarrhea, and excessive salivation.

Carbaryl is lethal to many non-target insects, including bees and beneficial insects.

The best product to use is Bt. It only targets the caterpillars and is safe for humans, beneficial insects and the environment.

Here's a link to the Extoxnet the Extension Toxicology Network. You can search for any pesticide and see research results on how toxic it is.

Here is a link that might be useful: Extension Toxicology Network


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RE: Grape Problem

Thank you! Will do AZtreelover! We have been picking them off and killing them by hand but there are a great deal of them. Thank you for the site as well.


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RE: Grape Problem

I noticed few of my grape leaves looked eaten up...couldnt spot any caterpillars. i saw the bluish black fly laying eggs under leaf. I dont have any grapes on the plant, 3 yo plant never produced fruits.... Is it too late for the vine to be producting new fruit now ?


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RE: Grape Problem

A 3 year old plant should produce fruit. Not sure what is wrong, but it should. Are you giving it enough water and fertilizer?


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RE: Grape Problem

Actually, if the larvae have defoliated the vine, the will begin to feed on the grape clusters...this can lead to bunch rot. Also....if the vine becomes defoliated, you can find sunburn on the grapes which means they won't taste very good.


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RE: Grape Problem

I need to add fertilizer to grape vine, probably it too hot now for that? I have skeletonizers on my grape vine. The plant is not that big, 4-5 foot tall vine, so i check under leaves everyday and crush out the eggs, remove the caterpillars. I had ignored another thing which is causing the plant to look unhealthy. there are tons of leafhopper type bugs on it on the leaves i thought they were harmless but they are damaging the leaves. They are tiny aphid like bugs which hop from leaf to leaf brown in color. I got some insecticidal soap spray (ecofriendly) sprayed the plant, got rid of bunch but many of these bugs hopped away and came back. Any better sprays out there that are more effective?


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RE: Grape Problem

i have a grape arbor.
i get up early and swat the adults, they seem to emerge from the ground and mate around dawn. with a fly swatter and a jet of water you can clear them out in a few minutes.

then i wash the leaves with a strong jet, i'll find lots of caterpillars on the ground, ready to die in the days heat, if i dont step on them first. i think it washes some of the eggs off as well.

i spray BT once a week, in the evening, being sure to wet the leaves on the underside. i pick any leaves with damage and get rid of them. i have a thick mulch of shredded weeds, with potatoes, onions and beans growing at the base of the vines, watered with a soaker hose under the mulch.

i'd like to know if anyone has looked at the parasitic/beneficial nematodes to kill the larvae in the ground?


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RE: Grape Problem

Just wanted to post that the skeletonizers came out this year, but I jumped on them quickly, spraying the plants with a solution of BT...

That was it... I did it twice, and they didn't get very far. The BT stuff works fantastic, and love that it's non-toxic to humans but very toxic to the the skeletonizers.


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RE: Grape leaf Problem

I have tiny black bugs on my grape vine but only on the ends of the new shoots. There is also one leaf with strange pinkish blobs on them. Can anyone tell me what they are and how to get rid of them?
I have pics here.


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RE: Grape leaf Problem 2nd pic

I have tiny black bugs on my grape vine but only on the ends of the new shoots. There is also one leaf with strange pinkish blobs on them. Can anyone tell me what they are and how to get rid of them?
I have pics here. 2nd pic.


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RE: Grape leaf Problem 3rd pic

Sorry, but I don't know how to upload more than one pic at a time!


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RE: Grape Problem

The pinkish blobs could be scale insects or possibly a rust of some kind. You can smash or dislodge a scale insect but a rust is a fungus. The small insects look like aphids but I can't enlarge enough to be sure. Anyone else have ideas?

Here is a link that might be useful: Grape pest


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RE: Grape Problem

I was thinking scale too...hard to tell with the poor focus. Black aphids.

No matter, if the grapes are past season you could just let them have their fill pooping out what will eventually dry up anyway. This would also feed the predators bound to show up.

Alternatively, hit them with a hose to dislodge. Follow up if they return (or if a stream of water fails to dislodge them which would be diagnostic) in a couple of weeks with insecticidal soap.

edit: If this (these) are first year grape vines then it is worth battling for them. With first year you want as much sugars made as possible to help establish those roots, so removing feeders makes sense. Grape are so good at establishing that after a year the vine should be able to withstand a large amount of predation and I generally wouldn't bother.

This post was edited by Fascist_Nation on Wed, Jul 23, 14 at 17:34


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RE: Grape Problem

Thank for your comments. I have blasted the leaves with the hose and it seems to have gotten rid of the black bugs.
With the pinkish blobs, I removed the leaf and have not found them any where else.
I have 3 different grape vines that I planted 3 years ago and never had any fruit and they we didn't grow a whole lot. Seems like this year they are finally growing well. We'll see.


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RE: Grape Problem

nice job. Low impact pest control.


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