Q. Should I cut out the limbs with all the brown needles on my Arizona cypress? The needles stopped falling off immediately and the one’s left don’t look nearly as brown and dry. I have no idea how to go about pruning these huge trees. Don’t know if it would help. What do you think? A. I would wait a bit. It is now the beginning of April. I don’t know what will happen in a month.
Arizona Cypress Pruning and Pest Problems Read More »
Q. I have a Kadota fig tree that gives lots of figs, but they are either hard as a rock or suddenly get mushy and fall off the tree. What am I doing wrong and how can I get some edible figs A. There are at least two crops of figs, an early crop (Briba crop) and a later crop (Main crop). My guess is that the early crop is getting enough water (when its cooler) but not the later crops. Remember, figs are water loving crops. As temperatures get warmer, they require more water. Also, as your fig tree gets bigger it will require more water. Prune them small and harvest the fruit from the ground when possible.
Kadota Figs are Treated Like Any Fig in the Desert Read More »
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.
Skeletonizers on Grapes a Late Spring Problem Read More »
Q. Our chitalpa tree underperformed last year after ten years of growth. This year (2024) it is 2/3 dead. How do I tell if it was verticillium wilt disease or bacterial leaf scorch disease that killed it? If leaf scorch, can I replace it with another Chitalpa? If verticillium wilt, what flowering tree resistant to verticillium wilt would you recommend? A. Chitalpa is a mesic hybrid between the catalpa tree and desert willow. In case you haven’t seen it, I would refer you to New Mexico State University’s fact sheet on chitalpa and bacterial leaf scorch. https://plantclinic.nmsu.edu/documents/xylella-fastidiosa-factsheet_reduced.pdf My guess is that this tree was infected, or already infected, by this bacterial disease. I would NOT replace it. I would pick a different tree other than chitalpa. Why? It is probable it would get reinfected with the same disease if it hasn’t been propagated with it. A different disease you mentioned is a widespread fungal disease called verticillium wilt. According to UCCE Sonoma County…. (Verticillium wilt is a fungal disease) caused by a soil-borne fungus that enters a plant through its roots and disrupts its vascular system. Symptoms of this disease include: With some trees they display discolored wood. This disease is less likely a problem with chitalpa. Both eventually kill the tree or at least they are infected. Verticillium wilt is a fungal disease that causes many trees to wilt rapidly. This fungus (disease) can live in wet or moist soil for long periods without showing any signs. The disease plugs the xylem, or water-conducting tissues, of the plant. In both cases, (bacterial leaf blight vs verticillium blight) whichever disease it might be is a moot point. Both diseases are lethal to the trees. The tree will eventually die and there is nothing you can apply to save it. If the tree has either of these diseases, it should be removed. I would not recommend planting a new chitalpa. That is unfortunate because chitalpa is one of the few trees that is smaller, can handle our heat and fits nicely into our small tree palette even though I put it in the “mesic” category of water use for trees. With bacterial leaf blight (more likely) it is spread by insects. It is spread by the same insect responsible for a grape and oleander diseases. Because it is primarily spread by insects, it is pressing to remove the tree in summer as soon as possible. Verticillium wilt disease (less likely) is not spread by insects, so it is less pressing to remove it asap. It is related more to wet soil and usually not spread by insects. In both cases they are always lethal and not curable. Verticillium disease resistance is less likely in small trees in the rose family, pines (gymnosperms), and palms (monocots). Since this disease is more related to wet soil, I would not plant anything in the same hole but avoid planting in the same spot. If I had to replace the tree with something in the rose family, I would find a plant for that spot that gets afternoon shade and prune it to the height needed. Smaller trees less likely to display problems in desert landscapes to verticillium wilt include: Purple leaf plum, larger boxwoods, hawthorne, many fruit trees like peaches, plums, and apricots, some of the smaller conifers, crepe myrtle, citrus, ornamental pear and pear trees, katsura tree, palms, flowering cherry, pyracantha, honeylocust, and some of the hollies. All of these trees are mesic in their water use. Don’t water them daily!
Chitalpa Died Back Read More »