Snail Control for Organic Gardens
Snail problems in organic gardens occur with regular frequency along the West Coast and the Southeastern the United States.
Most, but not all, garden snail problems are caused by non-native snail species which thrive in temperate, moist climates, spring and fall typically mark the height of snail season.
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The top picture, for example, shows the brown garden snail (Cantareus aspersus or Helix Aspersa), a species native to Europe and introduced into California in 1850 as a food source.
Since its early introduction, the snail's range has spread up and down the entire West Coast.
Identifying snail pests can be a relatively straight forward task, with the shell serving as the key field identification clue. While the Brown Garden Snail shell varies from individual to individual, generally between species differences are sufficient for identification purposes.
The three additional native snails presented below provide examples of snails not commonly thought of as garden pests.
The Robust Lancetooth (Haplotrema vancouverense), a very common West Coast snail, often found in forests, belongs to the predatory Haplotrematidae family.
Their predatory nature makes them beneficial garden snails, capable of preying on other snail and slug pests.
Its shell color ranges from a greenish to an orangish color and assumes a flat rather than domed shape.
Sideband snails, genus Monadenia, live in Western forest areas. The dark band on the side of the otherwise brown shell represents the first, good field identification clue.
Generally Monadenia species avoid garden pest status. Research on Monadenia species population levels remains incomplete, however concerns exist regarding population levels for a few species.
The colorful Florida Tree Snail (Liguus fasciatus) inhabits hardwood forests of south Florida.
Far from being considered a garden pest, the state of Florida lists it as a Species of Special Concern, and they contribute to south Florida biodiversity.
Organic remedies for garden snails often take four different paths: baiting; barriers; biological; and manual.
- Baiting refers to the practice of placing lethal food in a snail's path. Consumers have a choice of two commercial baits, a toxic metaldehyde based produce and a less toxic iron phosphate product. The iron phosphate product is the organic gardener's best bet. Snails are also attracted to the odor of yeast. Placing beer or other yeast based liquids in containers around the garden, lures the snails into the containers, eventually drowning them.
- Physical barriers such as copper sheeting commonly prevent snails from reaching container plants.
- Manual removal strategies can take one of two forms. Since snails are most active during the night, inspecting the garden for snails prior to bedtime, and manually removing them, eventually reduces the overall population. While placing boards around the gardens will not act as a barrier against snail predation, snails often use the boards as day time rest stops, thereby making manual removal of the snails during the day a bit easier. Once captured, experts suggest dropping the snails in a bucket of soapy water to drown them.
- Biological controls such as the use of predator decollate snails are recommended in cases of extreme snail infestation covering a large area. For small home gardens, successful implementation of the first three options usually solves the problem.
© 2009-2012 Patricia A. Michaels