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United States Department of Agriculture

Agricultural Research Service

Research Project: POSTHARVEST TREATMENT OF TROPICAL COMMODITIES FOR QUARANTINE SECURITY, QUALITY MAINTENANCE, AND VALUE ENHANCEMENT Title: Methods for Excluding Slugs and Snails on Exported Horticultural Commodities

Author
item Hollingsworth, Robert

Submitted to: Recent Advances in Postharvest Technologies of Horticultural Crops
Publication Type: Book / Chapter
Publication Acceptance Date: January 15, 2007
Publication Date: December 31, 2009
Citation: Hollingsworth, R.G. 2009. METHODS FOR EXCLUDING SLUGS AND SNAILS ON EXPORTED HORTICULTURAL COMMODITIES. Postharvest Technologies for Horticultural Crops. Vol. 2: 93-119.

Interpretive Summary: In recent years, various species of slugs and snails (mollusks) have become more important as quarantine pests, threatening agriculture, export markets and the environment. The increased pest status of these organisms is due to the rapid spread of damaging species which has been associated with increased international trade of horticultural commodities. Plant propagative material and other types of horticultural commodities are types of exports likely to be infested with quarantine species of slugs and snails. However, slugs and snails are also commonly intercepted in or on other types of cargo, including household tiles, sea freight containers and any type of commodity or object allowed to rest on bare soil before being exported. For those types of horticultural commodities frequently infested, the likelihood of infestation in a particular consignment is largely determined by the effectiveness of the control measures used before harvest. Standard control measures employ food baits poisoned with metaldehyde, methiocarb or (more recently) iron phosphate. As useful as these materials are, they are far from 100% effective. Sprays containing heavy metals such as copper are repellent and/or toxic to slugs and snails and provide good control under some circumstances, although they have many practical limitations. A large number of botanical extracts are active against slugs and snails, particularly as repellents, but only a few are commercially available. New discoveries in this area, combined with improved formulation techniques, are likely to result in a variety of new and useful products. Post-harvest control measures include hand-picking, fumigation, chemical and hot water dips, and the use of repellents. Irradiation is a potential control method, but little research has been done. Of these measures, fumigation with methyl bromide is the most effective, but is relatively expensive. Also, not all crops will tolerate treatment with methyl bromide. Overall, the most practical methods for excluding mollusks include good sanitation, repeated pre-harvest control measures when infestations are present, and careful inspection of the commodity followed by an approved post-harvest treatment when quarantine species of slugs and snails are discovered in the consignment.

Technical Abstract: Increasingly, slugs and snails (mollusks) are recognized as important quarantine pests threatening agriculture, export markets and the environment. This increased awareness results from the rapid spread of damaging species concurrent with higher levels of international trade of horticultural commodities. Plant propagative material and other types of horticultural commodities are high risk exports for quarantine species of slugs and snails, although these pests are also commonly intercepted in or on other types of cargo, including household tiles, sea freight containers and any type of commodity or object allowed to rest on bare soil before being exported. For high risk horticultural commodities, the probability of slug and snail infestation at the time of export is largely controlled by the efficacy of pre-harvest control measures employed. Standard control measures employ food baits poisoned with metaldehyde, methiocarb or (more recently) iron phosphate. As useful as these materials are, they are far from 100% effective. Sprays containing heavy metals such as copper are repellent and/or toxic to slugs and snails and provide good control under some circumstances, although they have many practical limitations. A large number of botanical extracts are active against slugs and snails, but only a few are commercially available. New discoveries in this area, combined with improved formulation techniques, are likely to result in a variety of new and useful products in future. Post-harvest control measures include hand-picking, fumigation, the use of chemical and hot water dips, repellents and irradiation. Of these, fumigation with methyl bromide is the most effective, but is relatively expensive and not all crops will tolerate the treatment. Overall, the most practical methods for excluding mollusks include good sanitation, repeated pre-harvest control measures when infestations are present, and careful inspection of the commodity followed by an approved post-harvest treatment when warranted.

Last Modified: 10/25/2014
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