Nematodes are microscopic roundworms that live in soil. They are one of the most diverse groups of animals on the planet. There are potential millions of different nematodes, but only about 28,000 identified nematode species, and around 16,000 of those are considered parasitic.
Like many of the critters that exist in our gardens, with nematodes there are good guys and bad guys. Different varieties of nematodes fall on each side of the fence. Bad nematodes can parasitize roots of plants and cause leaf damage. Beneficial nematodes help the gardener by eating a variety of pests. There are also nematodes that don’t hurt or harm the garden–they just hang out and eat bacteria in the soil.
Knowing which nematodes are which usually won’t happen until something goes wrong. If your plants are suddenly weak or stunted, it’s likely that root-knot nematodes are wreaking havoc below the surface. Nematodes generally attack the roots of tomatoes, potatoes, okra, peas, beans, sweet potatoes and peppers. One way to defend crops against destructive nematodes is to plant nematode-resistant crop varieties. Rotating crops can also help. Organic methods, like adding compost or crushed seashells to the soil can help attract good guys that will prey on parasitic nematodes.
Beneficial nematodes can help you get rid of a host of garden pests. While plenty of organic matter in the garden may attract them on its own, you can always purchase and add nematodes to take care of a specific pest problem. Just be sure you’re buying the right ones for the job–different nematodes feast on different pests.