Issue: July 29, 2006

Eco-friendly grub worm control in New Mexico.


I have 2 questions: (1) Is there an eco-friendly way to control grub worms in flower beds? I have a xeriscape yard with lots of agastache and other bird and butterfly plants that are planted in a meadow-type setting. The grub worms have destroyed many of these. I don't want to damage the earth worm population that I have finally built up in my yard, but the grubs are costing me lots in replacing plants. (2) What does the Master Gardener program consist of?
Kathy W.


Regarding your grub question - Have you confirmed that grub worms are doing the damage? The reason I asked is that cutworms and other moth caterpillars may be doing this type of damage. An organic (biocontrol) method to manage the problem (either grubs or caterpillars) is the use of insect parasitic nematodes. These extremely small round worms are not related to earthworms and should not harm the earthworms. One genus of nematodes (Steinernema) is effective against moth larvae (caterpillars), while another nematode genus (Heterorhabitis) more effectively controls beetle larvae (grubs). Nematodes are very particular in their choice of prey, so they will not harm many other insects and wild life in the garden. These nematodes are related to the plant parasitic nematodes but will not infest or harm plants. They can be killed by high soil temperatures, so the soil should be moist and cool before applying them. Nematodes do not travel great distances, so you will need to apply them where they are needed and when their prey are present. Parasitic nematodes are available from insectaries (selling biological control agents) and, increasingly, from garden supply stores. Dr. Whitney Cranshaw, Colorado State University Extension entomologist, has written a good article regarding insect parasitic nematodes. It is available on the internet at .

Regarding your Master Gardener question - The Master Gardener Program is a New Mexico State University outreach program to assist New Mexico gardeners by training volunteers who assist the County Extension Service agents. The Master Gardeners must attend classes and pass tests (not terribly difficult tests) under the supervision of the local Cooperative Extension Service agent. After training, the Master Gardener trainees become Master Gardeners by volunteering their time and service to educate their community with research-based gardening methods appropriate to their local environment (taught in the classes). This volunteer service is done under the guidance and authority of the County Extension Agent. The volunteer activities vary somewhat between counties according to the needs of each particular county. You can get specific information from your local Extension Agent. If there is no Master Gardener program in your county, your local agent can direct you to a nearby county with Master Gardeners.

back to top

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:, 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, or at the Desert Blooms Facebook.

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