Managing Slugs and Snails in the Garden

by: Sara on 03/21/2018

When my nephew was a toddler he had a fascination with slugs. He found those slimy, turd-like molluscs enchanting and would carry one...or a few...around with him everywhere. His mother tried to be supportive, like any mother when their child shows an interest in something, no matter how gooey an interest it was. She even took to trying to protect the poor things with containers as he waded into the ocean with them on a camping trip. (Yes as we well  know salt and slugs don't mix) Now the serendipitous part is that his mother, an avid gardener, did not have the same appreciation for their presence. So perhaps it was a gift that he would pluck them from the young, tender leaves and put them in his pocket.

As many of us on the west coast know, slugs wreak havoc on our gardens, and unless you have a child with a slug fascination around, chances are you need an alternative method of control. Luckily for us Linda Gilkeson, master gardener and the author of Backyard Bounty: The Complete Guide to Year-Round Organic Gardening in the Pacific Northwest, offers an alternative to small children for snail and slug control.

 

What to look for: Large ragged holes chewed in leaves and shoots of emerging plants. You can usually see traces of their slime trails on damaged leaves. Slug eggs are perfectly round, translucent, and laid in masses in the soil.

Fig. 9.23 slug eggs

Biology: Slugs and snails are essential decomposers of organic matter in our gardens, but they are also a West Coast scourge because they are most damaging in cool wet weather. Snails and some slugs climb up plants and shrubs to feed on leaves.

Management: Water in the morning to allow the soil surface to dry by evening.

Use drip irrigation or soaker hoses to limit the surface area of moist soil. Pull mulches well away from seedling rows until plants are well-grown. Patrol the garden in the evening or early morning to kill slugs. Lay boards, slabs of damp newspaper, or grapefruit halves on the soil, and kill any slugs hiding underneath in the morning. Use strips of copper or zinc mesh around the edges of planters and on legs of greenhouse benches to repel slugs (this only works if you are sure there are no slugs or slug eggs already inside the area).

Slug baits containing iron are very effective (several brands are approved for use by certified organic growers). Unlike the old toxic slug baits containing metaldehyde, these won’t harm pets or wildlife. Sprinkle the granules sparingly, but widely, over a whole garden bed, and replace after heavy rain. Don’t use it to encircle plants you are protecting because it is an attractant for slugs and acts slowly, leaving the slugs plenty of time to eat your plants before feeling the effects.

Fig. 9.24 slug trap

Spreading sharp materials, such as wood ashes, sharp sand, or diatomaceous earth (may be listed as silicon dioxide on the label), around plants is of little or no use, especially in wet conditions. Diatomaceous earth would also kill beneficial insects that walk across it.

Drown slugs by attracting them to containers of fermenting liquids (slugs love yeast). The bait container should have holes cut in the sides to allow slugs access, as well as a lid to prevent ground beetles (important predators of slugs, from falling in. Set the container into the soil with the holes just above the soil surface.

Fill it three-quarters full of beer, or use a mixture of water, baking yeast, and sugar.

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