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July 7, 2012

Getting rid of borers on apricot trees

Yard and Garden July 7, 2012

Q.

My apricot tree has borers. What would you recommend I use to get rid of them in a timely fashion?

Jim S.

via University-wide Extension website

A.

I contacted Dr. Carol Sutherland, NMSU Extension Entomology Specialist, since she has more current information on pesticide products labeled for in New Mexico.

Dr. Sutherland stated "this is always a tough question and the answers are generally not that helpful or encouraging." She made several recommendations that I will summarize below.

I often recommend parasitic nematodes as a treatment for peachtree borer (which attacks other stone fruit trees as well). She stated that parastitic nematodes may work, but they are not consistent. She pointed out that our summer heat and high levels of UV light are very harmful to the nematodes, reducing their effectiveness. She also pointed out that they must be applied in a manner that places them very close to the borer larvae if they are to be effective.

Dr. Sutherland mentioned several chemical pesticide options: Treatments with insecticides can also be challenging for homeowners. It is imperative to read product labels, specifically for instructions on the safe and appropriate use of insecticides for this particular pest on fruit producing trees. For those interested only in 'reduced risk' treatments, there are 6 products containing azadirachtin currently registered for use in New Mexico on this stone fruit pest. One or more of these should be available at nurseries, garden centers, feed stores, farm supply stores, big box stores with gardening supplies, etc. Verify that peachtree borer and stone fruit tree are listed on the specific product label.

She pointed out that insecticidal treatments are aimed at visiting adult females and potentially at hatchling larvae before they enter the bark. The bark and sap blobs will protect caterpillars already infesting the tree.

Products available to homeowners are not systemic so do not expect them to control larvae unless the larvae are directly contacted by the spray.

Dr. Sutherland quoted the common question, "Is there a most effective insecticide?" Her answer is that there are no silver bullets. There are also no 'single use' products either; expect to make periodic treatments during the season. She emphasized the importance of following directions on the label including those for safe application and storage. For each product under consideration, read the label for specific instructions on treatment of peachtree borer. For homeowners, there are products with permethrin, malathion or carbaryl, either singly or in combinations. There are other pyrethroids in some fruit tree sprays also, but again, verify the use of the product for peachtree borers and your fruit tree. Contact between the insecticide and the larvae is a 'must.'

For more gardening information, visit the NMSU Extension publications Web site at http://aces.nmsu.edu/pubs/_h, or to read past articles of Yard and Garden go to http://aces.nmsu.edu/pubs/periodicals.html

Send your gardening questions to:

Yard and Garden, Attn: Dr. Curtis Smith
NMSU Agricultural Science Center
1036 Miller Rd.
SW, Los Lunas, NM 87031.

Curtis W. Smith, Ph.D., is an Extension Horticulture Specialist emeritus with New Mexico State University's Cooperative Extension Service. NMSU and the U.S. Department of Agriculture cooperating.