Xtremehorticulture

Xtremehorticulture of the Desert

Skeletonizers on Grapes a Late Spring Problem

Leave a Comment / fruit, grape, grape insecticides, grape leaf eaten, grape leaf skeletonized, grape leaf skeletonizer, grape leaf skeletonizer pictures, Grape leaves damaged, grape leaves eaten, grape pests /

Q. I have some pest problems on my grapes that I think is grape leaf skeletonizer, but it made holes in the leaves. Is this the same skeletonizer or do I have a new problem? A. The grape leaf skeletonizer is an adult three quarter to one inch or so moth which lays eggs in clusters and is a problem with grapes every year. The short-lived adult moth, along with the small eggs, don’t do any damage. It’s the larva which burn like matchheads if they fall on your skin. It’s these larvae that “skeletonize” grape leaves that causes all the damage. These young black and yellow larvae glide across grape leaves and turn these leaves into “skeletons” three to five times every year. Skeletonizing grape leaves is what gets them bigger. This can start from April or May of every year in Las Vegas depending on their populations. If you don’t get some control of them early with sprays of spinosad or Bt, their populations may continue to get larger and larger. There is another insect problem with grapes. That is the grape flea beetle which “chews” holes in the leaves. Most of the time it can be confused with “skeletonizers”. This is because they occur at the same time, but don’t create the same type of damage. Flea beetles chew holes in leaves. They don’t skeletonize leaves. And, unlike ‘skeletonizers”, they cause grape leaf damage, at the most, twice year. Oftentimes, just once in the spring. With “skeletonizers” the preferred spray is spinosad. You can use Bt (Bacillus thuringiensis) sprays and most of the time they will work. I like spinosad sprays because they will get leafhoppers as well which Bt does not. For grape flea beetles any insecticide works. But spraying them with an insecticide isn’t always the answer. Usually, unless the infestation is heavy, just waiting three weeks is enough. The population of grape flea beetles will pass without spraying. I oftentimes will just wait for three weeks but not for the skeletonizers. You must spray and spray early. Don’t forget to spray the undersides of leaves early.

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Leaf Munching on Grapes, Whiteflies, Leafhoppers

4 Comments / grape insecticides, hornworms, leaves disappearing, whiteflies /

Q. My grapes leafs are gigantic this year after the big pruning; but something is taking big munching bites out of the leaves – I don’t see any thorn worms?  Any ideas? -Jeri One of the hornworms as larva or caterpillar A. It is probably hornworms this time of year. Put on a spray of Bt now or spinosad. Repeat it in about two weeks. Use spinosad if you had leafhoppers last year. They are tiny and they jump. That should keep them pretty clean. Q. I enjoy your articles in the newspaper. Thank you for your insights into my garden. I have a five year old grapevine.  Each year I have an infestation of tiny white flying insects.  I have tried traditional sprays with no success. What are they, and how do I get rid of them?  BTW – The hummingbirds love them.  The birds will cause the insects to become airborne, then pluck them off in mid-air. -Fred Leafhopper damage to grape leaf A. It is possible that they are either leafhoppers or whiteflies. I have seen leafhoppers more often than whiteflies on grapes. However your description fits whiteflies better than leafhoppers since you said they fly and are white.             Leafhoppers are usually darker in color, green or brown or a combination of both but jump into the air rather than fly. Both are hard to control but soap and water sprays are good when they are very young.             It is getting late now as this should have been applied in late April or early May if using soapy water. You can also use insecticidal soap. It is in the right concentration and does not have potential problems as you might have with soaps or detergents that have skin conditioners or scents added. Leafhopper damage cropped and enlarged upper surface             Be sure to spray the undersides of the leaves which is where they are most likely found but go out and find where they are and direct the spray on the insects, not just on the plants. The insecticidal soaps have no residual so if they land back on the soapy surface of the leaf it will not harm them.             The soapy water MUST come in contact with the insect or it will not work. If these are truly whiteflies then use a fruit spray that contains the words pyrethrums, permethrin, cypermethrin, pyrethroids, etc. you get the idea. It should have “ethr…” in words in the ingredients. There are lots of different kinds.             If this is leafhoppers you can try applying spinosad this time of year but it is starting to get late for this application. It should have been done in May but try it.

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