By Marilyn Pokorney
Slugs are major pests of horticultural plants throughout the
world. They are destructive pests of home gardens, landscapes, nurseries,
greenhouses, and field crops.
Slugs also pose a health threat to humans, pets and wildlife by
serving as intermediate hosts for parasites such as lungworm.
Slugs are inactive in cold weather and hibernate in the soil.
Heavy mulching and watering, required for productive and
beautiful gardens create favorable conditions for slugs.
Slugs destroy plants by killing seeds or seedlings, by
destroying stems or growing points, or by reducing the leaf area. Slug feeding
may also initiate mold growth or rotting.
Slugs feed on a variety of living plants chewing holes in
leaves, flowers, fruit and young bark. They are also serious pests of ripening
fruits, such as strawberries and tomatoes, that are close to the ground.
However, they will also feed on foliage and fruit of some trees favoring citrus.
Some plants that are seriously damaged include artichokes, asparagus, basil,
beans, cabbage, dahlia, delphinium, hosta, lettuce, marigolds, and many more
plants too numerous to list here. To determine if damage is caused by a slug or
other insect, look for a clear, silvery mucous trail.
Under ideal conditions, chemical baits, containing metaldehyde,
can be somewhat effective because this aldehyde paralyzes the slugs and they
eventually die from dehydration. However, under cool and wet conditions when
slugs are most active and troublesome, they can often recover. And these
chemicals are poisonous to cats, dogs, birds and curious children.
Biological control provides an attractive alternative to
traditional control practices. Nematodes possess exceptional potential as
biocontrol agents for pest slugs.
In Europe, a product as been successfully developed from
Phasmarhabditis hermaphrodita, that is effective against a wide variety of pest
slug and snail species and it targets only slugs and snails.
It would be a perfect solution for introduction into the US but
there are no published records of P. hermaphrodita occurrence in the US. Thus,
regulatory issues prohibit it's introduction and marketing in the US.
Slugs do play a positive role in the environment. Because slugs
are also scavengers eating decaying vegetation, animal feces, and carrion they
help in breaking down decomposing materials thus helping to release nutrients
back into the soil.
Slugs are night feeders so night traps and beer traps are the
best ways to catch and trap them. But there are many other methods proven
successful. One includes a very common, but not well known, ingredient.
For more information:
Marilyn Pokorney Freelance writer of science,
nature, animals and the environment. Also loves crafts, gardening, and reading.