Q Ugh! There are great big holes in the leaves of my plants! What do I do about them?

A Large holes in leaves – or leaves that have been eaten away altogether – are one of the most common signs of a pest invasion. Here are some of the possible culprits:

Slugs and snails
If you see slimy or shiny trails on the leaves, slugs or snails are the culprits. These pests hide under mulch, rocks, and other objects during the daytime and feed at night. They pose the biggest problem in wet weather.
Controls: Trap these pests under boards, cabbage leaves, flowerpots, or other objects, then scrape them into a bucket of soapy water to dispatch them. Or lure them to containers filled with stale beer: Set containers with the lip at soil level so that slugs and snails are lured in and drown. Surrounding plants with a band of wood ashes discourages them as well, as long as you renew it frequently. Attracting birds, toads, and other beneficial animals to the garden also helps control slugs. Organic slug and snail bait also is available. The active ingredient is iron phosphate and Sluggo is one brand name to look for.

Caterpillars
Various caterpillars feast on vegetable foliage, chewing large holes in leaves or devouring leaves completely.
Controls: All caterpillars can be controlled by handpicking or by spraying with Bacillus thuringiensis (Bt). Attracting beneficial insects will decrease problems with caterpillars, and if you see any that seem to be sick (they’ll be sluggish or yellowish in color, or have ricelike cocoons on them), leave them alone and let the disease or the parasitic wasp spread to other caterpillars. Spinosad is also effective against caterpillars.

Cucumber beetles
If you see “/6.35 mm-long yellow and black beetles – either spotted or striped – cucumber beetles are eating your veggies. Both feed on a wide variety of vegetables, and both carry various diseases that cause plants to wilt and die suddenly.
Controls: Use floating row covers on seedlings, and hand-pollinate crops such as squash and melons that need it to produce fruit. Apply parasitic nematodes to the soil to control the beetles” larvae, and spray pyrethrin or rotenone to control the adults. Kaolin clay is also effective against cucumber beetles. Be sure to clean up the remains of crops and dispose of them in the trash, since these pests overwinter in them.

Animal pests
Various animal pests can also chew leaves and plant parts, so don’t overlook them. Deer may eat entire plants, but they also can browse off the tops of your vegetables. Crows have been known to pull up seedlings and consume them, and rabbits are eager to chomp away at all manner of vegetable plants.

Reprinted from The Veggie Gardener's Answer Book
Copyright 2008 by Barbara W. Ellis, with permission from Storey Publishing.
Creative Commons photo credit: J. Star