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Italian cypress with foliage browning
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A. Major reasons for Italian cypress dieback: Too much water. Water deeply once 3 – 4 weeks in winter and no more than about once a week in summer. Too little water. Sometimes people put these trees on just a few minutes of water from their drip irrigation system. Water should be applied so that it wets the soil down 24 inches to an area at least four feet in diameter around the tree. Depending on how quickly enough water from your drip system is applied this might take up to several hours of applied water.
Spider mites. Starts in hot weather because that’s what they like. Usually a problem on trees that were underwatered. Spider mites like dirty foliage. Wash trees with a high pressure hose nozzle after dust storms or a couple of times a year just to keep them clean. Periodic soap and water sprays are not a bad idea either.
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| Webbing in italian cypress may or may not be due to the bad guys |
I found that simply using a pressure nozzle on the end of a hose washes off the webs, which tend to be mite colonies. These little suckers suck the juice out of the tree fronds. It pays to wash down the cypresses about 4 times a year at least, to control the mites, and to wash out dead needles from the tree.
The Italian cypress is very sensitive to insecticides, and may die off in areas where such is sprayed. One cannot apply enough neem oil or insecticidal soap to take care of the problem, so the water hose blast is still the best resort
I used some "super safe" environmentally friendly pesticide on it and it did no harm to the plant, but I wish I'd thought of your hose idea, as brushing the material out was a pain. I brushed it first, then used the "safe" insecticide so it could get in better. Also used quite a lot, and it did work. Poor plant still looked so sad after all that, the owner wanted it gone. I will keep a close eye out for those buggies from now on and next time, they get the hose!
I just dug up a small cypress like this on the request of its owner because of such browning. It was infested with small, light brown caterpillars and their webbing and droppings. I did kill the bugs a few weeks ago and brushed out much of the damaged foliage, which resulted in a bald and ugly plant. I don't know if the bugs were secondary to another problem the plant had or if they were what was killing it. It never had looked really great in the past year I've been on this job. Its root system wasn't as developed as I'd expect, either. Maybe it was a bad place for it to be. Anyway, the plant was in Beaverton, Oregon. I should have taken a picture of the bugs but I knew I'd seen them before and assumed they were a common problem.
Hello-after reading the notes the action to take if to cut off the brown branches but see if the bend first. I then check the roots for bugs. I live in phoenix az. The trees did better in the shade. Can I grow them in the sun? Will new branches grow back? Thanks
Let me answer the second part of your question first. I have never seen it grow back once the damage is done. And even if it did, the growth would be very slow. The most frequent reason for Italian cypress turning brown is irrigation. Usually watering too often. Their roots are sensitive to wet soils. If the soils stay wet, they will die from root rot. Another problem that happens often to these plants is spider mite damage during the hot summer. This is oftentimes after dust storms or if they have been sprayed with an insecticide for another reason. It is a good idea to wash the foliage down about monthly during the summer to get rid of wind blown dirt which encourages spider mites. A third problem is borers. I never used to think it happened to them but I was proven wrong. A soil drench of Imidicloprid in early summer will stop that. Below is a link to Italian cypress written by ASU that might provided some guidance. The fact that they did better in the shade makes me think theywere not getting deep watering. They should be watered 24 inches deep when watered but not very often.
http://www.public.asu.edu/~camartin/plants/Plant%20html%20files/cupressussempervirens.html
If repeated infestation of spider mites has turned them brown is there any way to make them green again?
Not really. The brown foliage will stay brown. The only way to make them look better is for new growth that stays green to grow out beyond or replace the brown damaged growth. If the damage is light then new green growth to cover it up will happen fast. If the damage is severe then it will take longer. But new green growth replacing the damaged growth is the only way to get it green again. What is dead will stay dead. That being said there is green paint and green dye that will color them green until this painted growth falls off. But it is good for a temporary visual fix.
Does Ironite help?
Ironite may help if it's an iron deficiency problem or the plants can't take up enough iron. Iron problems on plants are usually yellow first before they turned brown and die. If the cause of the Browning was from poor water management management and drainage problems then Ironite will not do any good. By the way, Ironite only works if the soil is not too alkaline (pH above 7.6)