Snails & Gerbera Daisies
Gerbera daisy (Gerbera jamesonii) is a colorful plant used in borders and flower beds in U.S. Department of Agriculture plant hardiness zones 8 through 11. Massive 3- to 4-inch daisy-like flowers in a wide range of colors rise above the low, leathery foliage of this plant from early summer to fall. Although gerbera daisy is fairly pest-free, they are sometimes plagued by snails that may hide under their large ground-hugging leaves.
The brown garden snail (Cornu aspersum, formerly Helix aspersa) and the white garden snail (Theba pisana) are the most common sails encountered in the garden. Although you may see these inconspicuous snails in the daytime while tending your gerbera daisies, you're far more likely to see their damage since they are most active at night. Snails chew irregular holes with smooth edges in plant foliage and flowers, sometimes snipping succulent growth entirely, and leave behind a silvery trail of slime.
Snails sometimes become a problem in gardens that afford them many daytime hiding places. Remove any stray boards, rocks or debris that may be in or near the garden and clean up weeds and low-growing ground covers. Installing a drip irrigation system can help reduce humidity, making the garden less hospitable to snails.
Handpicking is by far the safest and most effective method of eliminating snails if done thoroughly and consistently. Take a flashlight and a bucket of soapy water with you to the garden every night. Check the undersides of leaves and between plants for snails and pick off those snails you see before tossing them in the soapy water. Continue this nightly raid until you have a difficult time locating snails, then check weekly.
Barriers made of copper are useful if they can be installed where no plant foliage is overhanging close to the ground. When snails try to cross these barriers, it is believed that they feel a sensation similar to an electrical shock, causing them to back away. You will need to install a barrier that is about 4 inches tall, burying it 1 1/2 to 2 inches below the soil surface. Handpick any snails that are trapped inside the barrier, since they will be unable to escape.
A variety of traps have been devised for snails, including shallow pie pans baited with beer scattered throughout the garden. An upside-down flower pot or wooden box are as effective as these drowning traps if you check them daily, scraping away any snails or eggs you find. Drowning traps should also be checked daily, so you can remove any bodies that have accumulated and change or refill the beer as needed.
Snail bait is a very effective control method when used in conjunction with cultural modifications and barriers. Safety with these baits is a real concern, though. Metaldehyde baits are dangerous for pets and children, as well as having the potential to damage plants. Iron phosphate baits, on the other hand, are safe for mammals, birds and fish, and break down into trace minerals in the garden. Scatter snail bait on a dry day, replacing or refreshing baits weekly, as needed, or any time after it rains.
- University of California Statewide Integrated Pest Management Program: Gerbera Daisy
- Cornell Cooperative Extension of Oneida County: Gerbera Daisy
- Arizona State University: Gerbera Jamesonii
- University of California Statewide Integrated Pest Management Program: Snails and Slugs
- University of Vermont Extension: Slugs and Snails
- Martin Poole/Digital Vision/Getty Images