Issue: April 13, 1998

Grub worms in the garden

I live in Albuquerque. I was turning the soil in our vegetable garden and have discovered grubs. We also have a good population of very fat earthworms. Do I need to take care of the grubs before we begin planting? How do I take care of the grubs but leave the earthworms?

There are several types of grubs, not all are a concern. The worst are those which infest our lawns. They may be found in gardens, but usually not in great quantities. These "bad" grubs feed on grass roots and cause serious problems in the lawn. They can feed on other plant roots, but unless the plants are dense, the female is not interested in laying her eggs in the garden. There is another type of grub which feeds on decaying organic matter. One of these is often found in manure piles and may wind-up in a garden when the manure is spread in the garden. This type will also be found in compost piles, another way it can get into the garden. I suspect you have a compost/manure feeding grub which would not be a problem. If you had a good garden last year and a lot of organic matter in the soil and a lot of plant debris decomposing in the garden through the fall, this is probably the case.

If you are not certain that these are debris feeding grubs and want to be certain that your vegetable roots will not be eaten, you can apply granular diazinon to the soil according to directions on the label for use in a vegetable garden. Be certain to check these directions and that the product is labeled for use in a vegetable garden before you purchase the insecticide. As for the earthworms, most should not be harmed and there are others deep in the soil which will come to replace any that are killed. The fact that the earthworms are present in your garden indicates a good quantity of organic matter in the soil and suggests again that these may not be grubs to worry about.

Growing lettuce in New Mexico garden

Every year I try to grow lettuce, but in the heat they never form heads, they just make flowers. What should I do?

According to George Dickerson, NMSU Extension horticulture specialist, who works with vegetable crops, head lettuce is grown as a spring or fall crop in Southern New Mexico, but that the head lettuce varieties are more difficult in Northern New Mexico. In the northern part of our state he recommends leaf lettuce or the cos (Romaine) or butterhead types.

In the long days and heat of summer, lettuce tends to bolt, or form flower stalks before forming a head. Then the winter is too cold to grow the lettuce. Use of these other lettuce types allows you to harvest home-grown lettuce before bolting occurs.

Since the lettuce is grown for the leaves, not flowers and fruit, less light is needed so you might also try planting on the north side of a home. In this shady location, the heat is less intense and you might have more success with all varieties. Still, the non-head types would be the most likely to perform well for you.

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!