Growing the Desert Garden

Welcome to the Desert Garden, with garden coach Tyler Storey, where we talk about everything having to do with gardening and landscaping in the Desert Southwest. From composting to Cercidium and agaves to arugula — we'll cover everything you want to know to grow your own beautiful Desert Garden.

Wednesday, April 30, 2008

From the Inbox: Spider Mites on Italian Cypress

From a Correspondent:

I live in Gilbert, and am looking for some help in saving my Italian Cypress. I planted 4 Italian Cypress in May 2007 each 5 gallon size. They have been doing very well (now almost 8+ gallon size) until a few days back. Out of four, I am seeing a problem in two of them. They look whitish or pale, dusty from the bottom, and have spider webs. I suspect spider mites, but am not sure. They get water regularly. I am wondering what is going on. Thank you for your time.
Regards
Rajesh, Gilbert, Ariz.

Rajesh, good afternoon,
From the picture you attached (below) I would say your diagnosis is spot-on: you have spider mites on your Italian Cypress.

Spider Mites on CypressMites aren't true insects, but rather arachnids. Mite infestations are increased by cultural conditions; hot, dry, and dusty conditions greatly favor their development. Importantly, broad-spectrum spraying of insecticides in the landscape tends to increase mite populations and their damage, sometimes explosively, because it eliminates their natural enemies. Some insecticides have even been found to stimulate mite reproduction directly.

There are two things you can do to try to control your existing mites, both fairly easy because your plants are still small.

First, once a week, in the morning, hit the plants, especially the infested area, with a strong blast of water from the hose – strong enough to really blast the little critters but not strong enough to damage the trees.

If that seems ineffective, use an insecticidal soap to spray the plants, being thorough and following the directions on the label exactly. There are miticides that are available, but those tend to be strong chemicals, and are probably not necessary.

I have had great luck with the water-blast method.

To help prevent severe mite infestations in the future, wash off your plants occasionally during the hot and dusty times of the year, and limit or eliminate pesticide spraying in and around the landscape.

I hope this helps,

Tyler

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