Organic Pest Control: What Works, What Doesn’t

Enlarge Image Image Gallery The tomato hornworm, a thorn in the side of many tomato growers, claimed the No. 7 spot in our list of the 12 worst garden pests. ILLUSTRATION: KEITH WARD

Last fall, MOTHER EARTH NEWS launched our Organic Pest Control Survey to learn more about what works and what doesn’t when it comes to limiting insect damage in organic vegetable gardens. About 1,300 gardeners from across North America responded, providing new, region-specific insight into organic pest control.

Our survey had strengths and weaknesses. It included opportunities for open comments, which became the source for the practical tips in this article. But, although we asked many questions about specific methods, we failed to always list chickens and ducks, which we learned many gardeners regard as essential players in controlling Japanese beetles and other garden pests.

We were surprised by some of the results. For example, we suspected gardeners would report that coping with various root maggots was a challenge, but 90 percent of respondents reported getting good control with crop rotation. Similarly, flea beetles didn’t make the list of worst pests because most gardeners achieve good control by using row covers and growing susceptible greens in fall rather than spring.

Ultimately, the survey revealed 12 widespread garden pests that give gardeners grief. Here are the nitty-gritty details, including down-in-the-dirt advice on how to manage each pest, plus details on which pests are the worst in each region. (To see illustrations of each of the worst pests, check out the Image Gallery.)

1. Slugs took top honors as the most bothersome pest in home gardens, with 55 percent of respondents saying the slimy critters give them trouble year after year. Handpicking was highly rated as a control measure (87 percent success rate), followed by iron phosphate baits (86 percent) and diatomaceous earth (84 percent). Opinion was divided on eggshell barriers (crushed eggshells sprinkled around plants), with a 33 percent failure rate among gardeners who had tried that slug control method. An easy home remedy that received widespread support was beer traps (80 percent success rate).

Relying on bigger predators — such as chickens, garter snakes and ducks — appears to be the most dependable way to achieve long-term control of garden slugs, as well as several types of beetles, cutworms and many other pests. Ducks are reportedly sharp slug-spotters, whether you let them work over the garden in spring and fall, or enlist a pair to serve as your personal pest control assistants throughout the season.

“Hungry ducks follow me around the garden daily. They love slugs and turn them into eggs,” commented a Mid-Atlantic gardener with 10 to 20 years of experience. In the Pacific Northwest, several longtime veterans of slug wars said ducks are a gardener’s best (and most entertaining) way to end chronic problems with slugs.