Q. I have three Italian Cypress trees that are 20 feet
tall. I have a problem with spider mites
and want to know the best way to reduce their populations. I started spraying them with high pressure water
and it got rid of all the webs. Since the trees are so tall I cannot
effectively apply a pesticide using my Ortho sprayer and garden hose.
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| Webbing in Italian Cypress does not always mean spider mites. You need to do the paper test explained below to see if mites are the problem or not. |
A. How did you confirm that the problem is spider mites?
They are easy to misdiagnose and there are problems that can appear like spider
mite problems and they are not.
For instance, not all spider
mites create webbing and not all webbing in Italian Cypress means it has spider
mites. You can find webbing in Italian Cypress from spiders that are actually
good guys and helping you out.
Spider mites normally occur
during hot weather. We seldom see them during cooler weather.
An Italian Cypress which has
spider mites will have the green needles or foliage beginning to die or turn
color, usually grey first. If I look at these needles they will have a dusty
appearance if spider mites are present.
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| Spider mites are extremely small. This one is highly magnified. They are about the size of the dot at the end of this sentence . |
I then hold the white piece of paper in bright sunlight very still for 15 to 30 seconds. If mites are present, I will see tiny little dots the size of a large period crawling around on the paper. If I brush my fingers lightly across this moving dot on the paper, I will see red smears on the paper.
If the Italian Cypress appears damaged, the foliage or needles appear dusty and I get red smears on the white piece of paper I will conclude the damages from spider mites.
Soap and water sprays are somewhat effective if done on a regular basis (couple of times during hot weather or after a dust storm) as a preventive. Otherwise you would have to apply a miticide effective against spider mites for good control. You would apply two applications about ten days apart to control the hatching of young mites from eggs which are not controlled with the first spray.
Unfortunately this would require that you spray the entire tree if mites are a problem. It is really hard for homeowners to spray much above 10 feet. I do not know of any miticides that you can apply to the soil and get good control.
First, make sure the tree has spider mites and that is the problem. Insecticidal soaps are good first choice but they are not extremely effective in controlling this pest. If you do get it confirmed that it spider mites and they are out-of-control, you will have to spray miticide. Watering Italian Cypress too often causing root disease problems can give them a similar appearance as branches begin to die.
Spraying trees above 10 feet is difficult for homeowners. Pest control operators and arborists have equipment to do this.
Would azadirachtin soil drench kill spider mites? I'm not referring to neem oil but to azadirachtin, active ingredient in products such as Azaguard, Azamax, Azatrol and others.
ReplyDeleteThank you for this informative article.
ReplyDeleteWould azadirachtin soil drench help fight spider mites when it's impossible to spray?
I don't mean need oil, which is effective only as spray, but azadirachtin the active ingredient in products such as Azamax, Azatrol and others. I've read azadirachtin is systemic, is taken up by the roots and moves upwards in the tree. Would greatly appreciate your comment on this.
I have used neem products for years because of the marketing and encouragement of its use on the Internet. I have had mixed results. I will admit I am not a huge fan of neem products but I use them in rotation with other things like soap, oils, Spinosad, Bt and pyrethrin depending on the insect problem.
DeleteI don't know the products that you're mentioning by name.I will tell you as much as I know about neem and its use under the circumstances that you mention. This is a product that has a lot of hype. It is systemic but is considered mildly systemic. It decomposes fairly quickly and sunlight. It is considered a good product repelling insects feeding on plants whether it is used as a foliar spray or applied to the soil as a root absorbed systemic. I could not find any solid recommendations using it against spider mites. It has a reputation for having erratic control of pests. For instance, it can control locusts but not grasshoppers. This is probably because the source of azadirachtim is not regulated in neem products or it could be the insect themselves. It might also be because of the insect and how it feeds. For instance, it has a reputation for controlling some aphids but not others. This makes it very hard to recommend and doesn't give general users much confidence. There is a lot of garbage out there. Some people swear by it and other people like me are on the fence. I can't tell you to use it unless Italian cypress or ornamentals and spider mites are on the label. It is up to you whether you want to try it or not.
I have 35 ft Italian Cypress whose leaves are turning yellow in patches. What is wrong and how can I control it? one tree has already turnes all brown, can that be recovered too?
ReplyDeleteThe three possible reasons I can think of include irrigation problems, spider mites, borers, Irrigation. Watering too often can cause roots to suffocate. Yellowing of the top can be a reacation to water soaked soils. Make sure soil dries out between waterings. This might require anywhere from one to three days or more during the summer months in the desert. The best way to judge soil moisture before watering again is either by feeling the soil at 8 to 10 inches deep or use a soil moisture sensor to judge when the soil is starting to dry out. When about half the water is gone from the soil after an irrigation, it is time to water. Spider mites can cause yellowing and browning as described above. This almost always happens during the summer months. If its in the summer look for webbing in the branches and use the paper test as described above. The third reason is borers. Recently borers were confirmed in Italian cypress. Soil applied insecticides like imidacloprid give some long lasting protection from borers But if you are seeing the results from borer damage int he tops of the trees, most of the damage has been done to the trunk and it might be a bit iffy to recover the tree. Doesnt mean you dhouldnt try. It just means dont be surprised if the tree dies, particularly if the damage is seen during the summer months and you have a couple of months of hot weather left. An example of imidacloprid is the Bayer Tree and Shrub insect control pesticide. Follow the label.
DeleteI appreciate your reply
DeleteAm totally at a loss at this point and I have read everything above. :-( I have 35 Italian Cypress which started getting webs in early March and in the desert in southern Nevada. I am told that there is no real "systemic" solution to get rid of them - relegating myself to spraying the trees almost weekly. Of course, soon they will grow out of the range of the "hose power." Looking for anything that works as I really want to keep the trees and 35 were $$$. PM me at randperry@hotmail.com if you have any updated/current solutions.
ReplyDeleteIf this damage is progressing during the cool months of spring and fall it is probably not spider mites. They get worse during hot weather. However, spider mites are there during the cooler months and this is a great time to control them before they become a problem. This is where the oils come into play. during the cooler months. I am referencing the University of California IPM notes which I reference back to for updating. The traditional miticides kill spider mites. For sure. Those are things with the active ingredients I mentioned above. But the problem with those products is they can create outbreaks of other insect pests so they should be reserved for when nothing else works or you are in a panic mode to save your Italian cypress. But watch for outbreaks of other pests one week or more later during hot weather. I am not tellin you NOT to use them, just be careful with them. If the problem is spider mites they are not difficult to erradicate as I mentioned. Its just that you upset the apple cart so to speak. Make sure the problem is from spider mites and not watering too often or poor drainage. Here is where I think a layer of wood chips 3 to 4 inches deep on top of the soil may halp. But be careful with woodchips because they will slow water loss from the soil and may cause the problem to worsen IF it is a watering problem. The major advantage of woodchips on top of desert soils around roots is giving the feeder roots a place to grow when the soil gets hot.
DeleteMiticides (insecticides) that kill mites contain the active ingredients of dicofol (sometimes called Kelthane and an organochlorine product,sometimes found in combination with herbicides and other insecticides), Pyridaben (sometimes referred to as Pyramite in the ingredients and another organochlorine), bifenazate (sometimes called Floramite among others and is a carbazate), that should get you going with chemical miticides. Follow a progression if you have time...spray the dust off with water, use oils during cooler weather, chemicals like these as a last resort.
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