Issue: Septe1ber 22, 2001

Reduce lawn irrigation in fall

Can I stop watering my lawn now that the weather has gotten cooler?

You should not stop watering your lawn. You can, and should, reduce the amount of water that you apply. As you do this, change the frequency of irrigation but not the amount of water apply with each irrigation. That means you should irrigate on fewer days, but each irrigation should moisten the soil to the same depth, providing the same amount of water to the soil. This will protect the deeper grass roots, preventing loss of deep roots and development of shallow roots which will be more subject to winter damage.

Because it is cooler, the grass will use less water, so the water in the soil doesn't need to be replaced as often. The grass is still alive and growing, so water is still needed.

The type of grass you are growing influences the amount of water needed. Warm season grasses, such as Bermudagrass and buffalo grass, are becoming dormant and use considerably less water. Cool season grasses are actively growing and still using water, but because of the lower temperatures they need less water. You will need to irrigate less often in warm season grass lawns than in cool season grass lawns.

Another consideration is that the trees and shrubs in the landscape also need water now. In fact, they are very active underground at this time of year growing and extending their root systems. Water is essential, but the plants are using less water now.

Cherry Slugs

My cherry tree has big problem with cherry slugs this year. What can I do?

Cherry slugs are the larvae of a saw fly and can severely damage leaves if the infestation is heavy. However, leaf damage at this time of year is not a major problem, but the problem may develop again next year if not treated. You can treat now, with little benefit except to reduce problems next year, or you can wait until next year to treat if the problem develops again.

There are a couple of treatment strategies. The first is chemical, and many pesticides are labeled for cherry slugs and effectively control this pest. Remember that these are not moth caterpillars, so Bacillus thuringiensis (an organic control chemical) will not work. A second treatment strategy is physical and involves the use of wood ashes from the fireplace of barbecue. Lightly moisten the leaves, then thinly apply the wood ashes to the leaves. The wood ashes are sharp, cutting the cherry slugs then drawing moisture from within the insect. This kills this particular pest. A word of caution - wear a dust mask and goggles when applying the ashes, especially if the tree is large and you must use a shovel to toss the ashes high into the tree. If you don't protect your eyes, you will experience the effects of these sharp wood ash particles. It will be very painful! If you choose a chemical pesticide labeled for cherry slug control, be sure to understand and follow the label directions.

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!