Issue: April128, 2001


Snails and slugs

Question:

I can't get rid of snails and slugs in my yard. It seems like when it rains, it must rain snails. Even when it's not wet here, I still have them. I've tried a powder substance, granules, beer traps and I even poured beer on the plants. My poor plants are just constantly being eaten by those darn critters. Is there anything else I can use?

Answer:

Snails and slugs are a problem in many landscapes, even here in New Mexico. They are often imported into the landscape with new plants. Snail and slug eggs, or the mollusks themselves (they are mollusks, related to oysters and clams - please don't ask me to tell you how to make them into escargot), may be found in the soil around the roots of many ornamental plants. Once they have been introduced into a landscape, they are difficult to eradicate. It is even difficult to keep their populations low enough to minimize the damage that they do.

Many people don't even know that they have snails and slugs in their landscape - they just find plants eaten by some secretive critter. As you have described, it is easiest to find them after a rain or irrigation. You may also recognize their presence by the silvery slime-trails that they leave on sidewalks or plant leaves. They lay down a layer of mucus (slime) as they travel across a surface. This slime protects them from sharp objects, even allowing them to crawl along the edge of a razor blade.

There are some techniques that do work to a limited degree to help manage snails and slugs. Some people have had success with copper screen or copper bands surrounding areas they wanted to protect from snails. Others have used bands of fertilizer around some plants. The fertilizer salt dehydrates the snails and kills them (like table salt, but fertilizer salts aren't harmful to plants if not over-used). If you wish, you can sprinkle a little granular fertilizer on the snails and slugs by hand, but this is time-consuming and only kills a few of them.

It seems everyone knows of the beer-filled traps into which the snails and slugs crawl and drown. It has been shown that non-alcoholic beer is also effective. A Master Gardener tells of snails being attracted to some mushrooms drying on her porch. She hand-collected and disposed of the snails. (The mushrooms didn't kill the snails but were an effective attractant.)

There are commercial snail bait products that may be used. Some products use chemicals which are quite toxic and should be used with caution where children, pets, and beneficial wildlife may potentially be affected. Another product uses iron phosphate. This is much safer to use and seems to be effective. A side benefit is the addition of both iron and phosphate plant nutrients to the soil.

There are also some predatory snails available through mail order insectaries (look for advertisements in gardening magazines). These snails eat other snails. They may also eat plants but are reputed to limit their damage through their cannibalistic nature (they eat their own kind, preventing damaging populations from developing).

Finally, when all else has failed, hand-picking (yuck!) after rains and irrigation may be employed. This is not extremely effective in ridding a landscape of snails and slugs, but there is the vengeance factor that some gardeners appreciate.

You may find it most beneficial to use several management methods in combination. However, if you use the predatory snails, do not use the other techniques at the same time as these techniques will kill the predators as well as the pest snails and slugs.

NOTICE:

LAS CRUCES 2nd ANNUAL ROSE SHOW will be held on May 12 at the Mesilla Valley Mall (between the J.C. Penney and Walgreen stores). Entries will be accepted from 7:30 to 10:00 a.m.; judging will be from 10:00 a.m. to 12:00 noon. Public viewing is from 12:00 to 2:00 p.m. The public is welcome to show their rose blossoms and to learn about roses in southern New Mexico. For more information call Tom at 522-5580 or Mary Ann at 496-7114.

ALBUQUERQUE 2001 SPRING ROSE SHOW presented by the Albuquerque Rose Society on Saturday, June 2 and Sunday, June 3 at the Albuquerque Garden Center, 10120 Lomas Blvd., NE. Entries will be accepted from 7:30 to 10:00 a.m. on Saturday. The show is open to the public on Saturday from 1:00 to 5:00 p.m. and on Sunday from 10:00 a.m. to 4:00 p.m.

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Send gardening questions to Southwest Yard and Garden, Attn: Dr. Marisa Thompson at desertblooms@nmsu.edu or at https://www.facebook.com/DesertBloomsNM/. Please include your county Extension Agent (aces.nmsu.edu/county) and your county of residence with your question!

For more gardening information, visit the NMSU Extension Horticulture page: desertblooms@nmsu.edu.

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, office: 505-865-7340, ext. 113.