Experts say slugs can destroy hosta plants

Experts say slugs can destroy hosta plants

Brian Jervis Ask the Master Gardener

“I love my hosta plants, but something is chewing on them. Suggestions?” – AG

Although there are many options for what gets chewed on a hosta, I'm going to guess it's a slug. Slugs are usually most active at night, so it's easy to miss these nocturnal feeders. Usually, it's those shiny/sticky trails they leave behind that help you determine that the problem is slugs.

You may have noticed that I didn't call them insects because the molluscs are gastropods, which identifies them as related to clams and mussels. Slugs can vary in size slightly from half an inch to over 4 inches in length. Slugs tend to lay between 20 and 100 eggs at a time in moist cracks in the soil or in your garden containers. The eggs hatch in about 10 days but maturing to adulthood can take from 3 months to a year.

The young make their way through the soil and eat seeds and roots. As they mature, they expand their diet to include leafy plants such as hostas. Slug damage looks like an irregularly shaped hole in the leaf with smooth edges.

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Since slugs prefer a moist environment, your first line of defense is to make sure your plants are not crowded and have plenty of air circulation. In addition, if you water in the evening, you should switch to watering in the morning. Watering in the morning is best for your plants but especially for your hostas. Moist leaves and mulch at night provide an ideal environment for slugs.

In terms of control, you have many options. Interestingly, slugs are attracted to liquids that have been fermented. For this reason, you can place several shallow containers such as a can of cat food or a disposable pie tin filled with beer around the hostess. The slugs will get into the beer, get stuck and drown.

You can also use scrap boards to trap slugs if you don't want to waste beer. Place the boards near your infected plants in the evening. When they have finished feeding for the night, they will retreat to the bottom of the panels. In the morning, you can lift the boards, then remove and destroy the slugs.

If this hands-on approach isn't your style, there are two chemicals you can use for control called molluscicides. The standard insecticides in your arsenal will not be effective. You may come across a molluscicide called metaldehyde, which is very common. However, products containing metaldehyde are not approved for use around edible crops and are toxic to dogs, so this product will not be on our recommended list.

There are better options that contain iron phosphate that are effective and will not put your dogs at risk. These products have names like Sluggo or Escar-Go! As always, follow the directions on these products for application. good luck.

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You can get answers to all your gardening questions by calling the Tulsa Master Gardeners Helpline at 918-746-3701, or visiting our Diagnostic Center at 4116 E. 15th St. Or email us at

    (tags for translation)botany

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