Issue: September 8th, 1997

Bark beetle treatment scam?

A man stopped at my house yesterday. He said he was inspecting trees in my neighborhood and that my pine trees have bark beetles. For a fee, he will treat my trees by trenching around them and drenching with insecticide. Is this really necessary? My trees look good. A Master Gardener told me that my trees don't have symptoms of bark beetles and that treatment would not be necessary. Who can I believe?

You didn't say who it was that inspected your trees. Was this a licensed pesticide applicator - or just a guy wanting your money? Based on your description of the health of your tree and the absence of symptoms and signs of bark beetle, I fear that this is not a reputable pest control professional that has "inspected" your trees. If bark beetles have infested your trees, it is too late to treat the infested trees. The beetles do their damage so fast that by the time you recognize that the trees are infested, treatment will not save the them. Your only option in this case is to treat nearby uninfested trees to prevent the beetles from attacking them. According to Bob Cain, NMSU Extension Forest Entomologist, the treatment recommended would not be effective even if there was tim to save the tree. Systemic insecticides absorbed by the roots will not affect the bark beetles which feed on the phloem. Chemicals absorbed by the roots do not readily enter the phloem and would therefore not control the bark beetles. All of this, along with the absence of bark beetle signs, sawdust on the bark and branches, the absence of pitch tubes, and the apparent health suggest that the Master Gardener gave you excellent advice. It is wise, however, to get another opinion from a neutral party when you are faced with conflicting recommendations.

Fruitless mulberry

We have a fruitless mulberry, for shade, in our back yard. It is about 10 years old. It has always had plenty of leaves until the spring of 1996 when I noticed there were fewer leaves than usual. This spring and summer they have had even less. Do you have any suggestions as to what is the problem?

There are several factors which could be causing reduced leaf production in your tree. The most likely are environmental factors. The winter of 1995-96 was very dry following a dry summer. Drought, especially in late winter, as root activity begins can cause reduced leaf production. The next winter, 1996-97, was wetter than normal, but there was a late freeze that damaged many emerging leaves as well as the branches and twigs. This could be the cause of the reduced number of leaves this year.

Other factors which could be causing problems are the salty nature of your soils around Roswell. In addition to being very calcareous, your soils often contain high levels of sodium chloride and other salts. This could cause the problems you described but would be accompanied with yellowing of the leaves and often browning of the leaf margins. Absorption of lawn herbicides by the roots of the tree could also be a cause if you used broadleaf weed control herbicides or weed-and-feed products. The reduction in leaves could also be caused by a need for additional nitrogen fertilizer or a change in your lawn irrigation practices.

Since you are familiar with your irrigation, fertilization, and weed control practices, you will have to consider and eliminate some of these factors; however, the weather conditions are still a very likely culprit.

Marisa Y. Thompson, PhD, is the Extension Horticulture Specialist, in the Department of Extension Plant Sciences at the New Mexico State University Los Lunas Agricultural Science Center, email: desertblooms@nmsu.edu, office: 505-865-7340, ext. 113.

For more gardening information, visit the NMSU Extension Horticulture page at Desert Blooms and the NMSU Horticulture Publications page.

Send gardening questions to Southwest Yard and Garden - Attn: Dr. Marisa Thompson at desertblooms@nmsu.edu, or at the Desert Blooms Facebook.

Please copy your County Extension Agent and indicate your county of residence when you submit your question!