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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Borers in Fruit Trees and Buggy Grapevines

1 Comment / flying insects, grape pests, jumping insects, leafhoppers, whiteflies /

Q. Through the years I have planted many fruit trees and lost many to borers especially stone fruit trees. My grape vines have been devastated by whiteflies to the point where I could not harvest one healthy grape leaf last season. I have tried soap water but to no avail. Also, I have tried Lindane against borers but their work keeps appearing on my plum trees. A. Whiteflies can be a difficult problem. We have not experienced whiteflies on grapes. The closest insect which might be confused with whiteflies, and is a common problem on grapes, are leaf hoppers. Please make sure you are not confusing whiteflies with leaf hoppers because the treatment is very, very different. Whiteflies are like dandruff and usually fly in a cloud of small white insects when the leaves are disturbed. They usually leave a sticky substance on the leaf surface from feeding. Click here to see some Whitefly pictures Leafhoppers on their backs, maybe 1/8 inch long Leaf hoppers on the other hand jump and are brown in color but they can accumulate in thousands on grapes and jump in your face, your nostrils and eyes as you pass the grapes and disturb the foliage. Both are nearly the same size but whiteflies are white and fly more delicately while leaf hoppers jump and are brown. If soap and water sprays are used religiously on the grapes when these insects are small it should give fairly good control. If soap and water is delayed until they are mature adults, then control is probably iffy at best. Whiteflies are listed on the University of California and pests lists for grapes but not a common pest. Leafhopper feeding damage on grapes Click here to learn the Common Pests of Grapes If they are whiteflies then sprays such as pyrethrins might be a good choice but the label must include grapes if you are to use it within the law. If these are leaf hoppers, then sprays applied in May such as spinosad might be useful when this insect is still juvenile. In both cases when these insects are adults they are much more difficult to control. Sap oozing from cut limb of plum Regarding the borers in your plum tree, Plum can be attacked by boring insects but it is not as common as some other fruit trees like peach, nectarine or even apple. Please check and make sure that this is in fact borers causing damage and not just sap oozing from a stressed out tree. When plum is stressed from water, intense sunlight or heat stress they will ooze sap. There is no insecticide you can use on fruit trees once they are attacked by boring insects and still safely eat the fruit in my opinion. Most insecticides recommended after fruit trees have been infested are usually systemic in nature. This means that the insecticide could also be in the fruit, not just on the surface.

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