Issue: September 30, 2000

• Spider mites on indoor avocado
• Globe Willow problems

Spider mites on indoor avocado

I have a 12-year-old avocado tree. It has spider mites. What is the best way to get rid of them? I've been battling them for about 6 years.

In our climate, an avocado is an indoor plant, so it will be important to use pest management practices that are useful indoors. If your tree is in an area with a tile or concrete floor (a floor that will not be damaged by water), spraying frequently with water may be sufficient to keep the mites from doing damage. They will survive, but their populations will remain low enough to be non-damaging. Smaller plants may be moved outdoors when the weather allows so that they may be sprayed with water. Larger plants on platforms with casters may also be moved outdoors and sprayed. The benefit of using water is the non-toxicity of the water to the person doing the application and the lack of potential damage to the plant.

Insecticidal soap should also be useful. It may be damaging to some plants (read the label for warnings), and some people are allergic to the soap. Soap may also be damaging to carpets, curtains and upholstery, so the plants must be in an area without furnishings which may be injured when the insecticidal soap is applied.

Use of water sprays or insecticidal soap on a frequent basis should keep the spider mites at bay; however, if the infestation is too severe, you may choose to apply a miticide labeled for use on ornamental plants. Such products must be applied out of doors when the weather permits. Read and follow all label directions.

Globe Willow problems

My Globe Willow is dripping and foaming sap. The bark is splitting and has a blistery look in places with a pink coloration on the surface and also in woody parts of the tree. I've been told that the heat causes the sap to "boil" out, but I really feel that it is more than that. Both upper branches and the main trunk of the tree are affected.

There are several things that could be involved to cause theproblem you are describing. One is borer insects. There are some diseases that could be responsible. Another consideration is a pruning cut that was made too close to the trunk, cutting through the branch collar and allowing disease entry into the trunk of the tree. It is important to determine the cause before an effective course of action in treatment may be determined. Contact your local Cooperative Extension Service office for help in diagnosis. The Extension Service is a service provided by your state university. It is there to help with problems such as you are describing. There is no fee for this assistance. In some counties there are also Master Gardeners, experienced gardeners who volunteer to assist the Extension Service staff. They will also be able to help you diagnose the problem and recommend a course of action. You can also get advice from local nurseries and garden centers.

I am sorry I could not provide more specific help in this circumstance. Since I did not personally inspect your Globe Willow, it would be advisable to contact a reliable source rather than guess at the cause of the problem.

Send your gardening questions to Yard and Garden, ATTN: Dr. Curtis Smith NMSU Cooperative Extension Service 9301 Indian School Road, NE, Suite 112 Albuquerque, NM 87112

Curtis W. Smith, Ph.D., is an Extension Horticulture Specialist with New Mexico State University's Cooperative Extension Service. New Mexico State University is an equal opportunity/affirmative action employer and educator.

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