Q. These are the worms we find on our Palo Verde tree in the backyard. We would like to get rid of them but do not know how. Is there something besides spraying the whole tree which is huge, a systemic maybe, that would do the trick and not kill the tree. They make a mess of the sidewalk and other stuff under the tree.  Any help would be appreciated.  Worms or caterpillars on readers Palo Verde A. These critters have been reported elsewhere in the desert Southwest. Must be because of our wet spring weather. They should disappear in a matter of a week or two or less. It is a larva or caterpillar of a moth. I am not sure which one.             Some caterpillars fold or roll leaves together with silk to form shelters. Others feed on leaves beneath a canopy of silk, sometimes creating “nests” in foliage, and others devour entire leaves along with stems.             Your tree can get a lot of damage from these critters and still be fine. If there is enough of them you should see a lot of their poop on the ground because they eat a lot, voraciously, before they pupate and begin the change into a moth.             You can spray with an organic pesticide such as BT or Spinosad but as far along as they are I think it’s a waste of money. Even if they defoliate the tree it will relief again and come back out.             Relax and have a glass of lemonade but don’t put your lemonade under the tree.

Q. I had a lot of bird damage in my apricots this year. Stark Saturn donut peach and bird damage. The birds love this fruit. It develops very high sugar content in the desert. A. The bird damage should be easy to correct if you harvest the fruit when it is still hard but has some color development. Keep an eye on the fruit and look for early bird damage. If the fruit has begun to change color, you can harvest when they are hard. Early producing apricots are less hard hit than the later ones.             Apricots develop the same sugar content as when it is left on the tree. Remember that sugar content does not equal flavor. Flavor is much more complex than just sugar content. It has a lot to do with the mixture of different chemicals inside the fruit such as the organic acids, flavonoids, etc.

Q. I have read that worm castings can be effective in eliminating aphid and white fly infestations. Is it effective on all insects that suck plant juices? What effect do worm castings have on beneficial insects? Are there any special instructions or precautions to be considered when using worm castings around fruit and vegetable plants?  Our own red wrigglers at work in a custom vermicompost bin A. You are one up on me on this topic. I have not seen any scientific publications that document this to be true in a general sense. If there are some, I would love to see them.  There is some work at Ohio State University that showed fewer insect problems on vegetables growing on vermicompost than without it. They focused on something the earthworms left behind called chitinase. research on vermiculture at Ohio State University There is some grant money right now for researchers working in this area. There are a lot of unanswered questions like how long can you use it, what does the quality need to be, how much do you need to apply and others.  Grant money There is no argument that vermicompost is a great soil amendment and may reduce the need for synthetic pesticide applications. There is some debate about “chitinase” and its effect on some insects. I think you have to be careful about jumping to conclusions on this one.             If chitinase is effective on insects it will be nondiscriminatory. In other words, it does not know the difference between a good insect and a bad insect.             Once leaf hoppers have matured and they are hopping around a lot when you pass by them they are difficult to control without conventional “hard” pesticides. I have never heard of worm castings used for anything but a fertilizer. That information about is new to me.             About the only organic method I know of that does a pretty good job controlling leaf hoppers is Spinosad. However, Spinosad has to be applied when leaf hoppers are immature in the nymph stages. It never totally eliminates them but reduces their numbers considerably if they are applied early enough and the sprays are directed where they are living.             As an example I have used Spinosad sprays in about May on grapes to reduce leaf hopper numbers. I apply the spray about one week apart for 2 to 3 applications as soon as I see the nymphs on the undersides of leaves.             I direct the spray upward so that the bottoms of the leaves are covered and then I repeat the spray on the tops of the leaves as well. To my knowledge worm castings have no effect on any kind of insect pests or beneficials. Treat it just as you would compost.

Q. My large Pine tree blew over. In researching on line I find there are lots of options to replace it. Most have con’s but I like the African Sumac, Raywood Ash, Weeping Willow and Poplar Trees. Please send me your recommendation on these or any other one recommended. I live in Mesquite, NV. A. Definitely not weeping willow or poplars. The other two are okay. Weeping willow is a very short lived tree in our hot desert and may last ten years if you are lucky. It needs to be next to a lake or river. Poplars of all types and weak and break easily in winds and very very messy. If you have some others you like then run them by me and I can give you a thumbs up or down. This is a good site to help you in your selection. Maybe someone out in that area has a favorite? https://www.snwa.com/land/design_plants.html

Q. We have two Chinese pistache trees in our backyard that appear to have verticillium wilt. Any suggestions? A. How did you confirm this disease? Do you have isolated branches that are dying back? It is rather rare to have this disease in a home landscape. Not impossible, but rare.If you are correct than this could impact your entire landscape and future plant selection.             I am sending you a link so that you can look at pictures of this tree when it has verticillium wilt. Readers can also see this link on my blog.  http://ipm.ucanr.edu/PMG/r605100811.html             There is not much that you can do if you in fact your trees do have verticillium wilt. It is fairly easy to diagnose if you know what to look for.             All you can do now is make sure the trees are not getting too much water, not fertilized with too much nitrogen and prune out the infected limbs.             This disease is in the soil so planting in this spot with susceptible woody trees is not a good idea. You can use ornamental grasses and pines in this spot since they don’t get this disease.