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Controlling Snails in the Vineyard with Bayer CropScience Mesurol Crop Protection

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Snails can seriously damage grapevines when they attack the emerging shoots in spring, or cause serious problems at harvest when it is common for thousands of snails to congregate in the vine canopy to commence their summer dormancy (aestivate).

The most important snails are the brown garden snail (Helix aspersa) and the white Italian snail (Theba pisana), with control best achieved by an integrated crop protection programme combining both chemical and physical methods.

Both species rely on shelter to breed and to protect themselves at certain times of the year. Such shelter may include plant litter, vegetation, rock piles or structures such as fences and posts, so a key to successful snail control is keeping weeds to a minimum, and the management of plant litter both under vines and in surrounding areas – roadsides, ditches and nearby buildings.

If snail numbers are high, baiting can be an effective strategy, noting that the snails need to be active for baiting to be effective, which is usually linked to moist conditions. Baits tend to work either by dehydration or through neurotoxic action which is the case with Bayer CropScience Mesurol. Unfortunately under moist conditions it is possible for snails to re-hydrate and continue to be a problem if dehydration is the only mode of action.

The best time for the effective use of Mesurol is early in the season, shortly after aestivation has finished, as snails are generally in a more voracious mood and readily attracted to the bait after this long dormancy period without sustenance and in preparation for mating. This timing reduces numbers before mating commences, and hence before numbers multiply.

Mesurol bait can be applied with a fertiliser spreader or similar equipment that will evenly spread the pellets on the ground beneath the vines. For existing populations within the vineyard an even spread will give better control than a narrow band of pellets placed directly under the vine row.

In addition, a 20-30cm band applied around the perimeter of the vineyard block in autumn or winter may also help to control invading snails.

The Mesurol formulation includes a very effective attractant, mould inhibitors, a hardener and a water repellent to ensure the product remains effective and long lasting even under adverse weather conditions.

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