Sprays
Sprays registered for snail and slug control contain methiocarb or silicate salts mixed with copper.
Sprays using methiocarb have a restricted registration and very long withholding periods when used on fruit producing trees and vines.
Sprays containing silicate salts and copper can only be sprayed onto tree trunks and vine canes, not onto foliage.
Sprays containing copper (Bordeaux mixture, copper sulphate or copper oxychloride) are not registered for snail control, but do have some effect, both in killing snails and slugs (usually juveniles) and in protecting plants by making them repellent. Bordeaux mixture contains one part copper sulphate to one part slaked lime to 100 parts of water.
Sprays are most lethal when applied when the snails or slugs are active. This is best achieved very early in the morning when the day is predicted to be fine, so that affected animals dehydrate before they can recover. This can be especially effective when snails or slugs are active on dewy mornings in early summer, when the effect of the sun is much greater.
Copper sprays can cause burning and fruit drop, especially in hot weather, so follow label directions closely.
Disclaimer: Recommendations were current when this information was prepared.