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Beneficial Nematodes: How to Use Them for Gardening
Good garden soil teems with life and activity. What goes on beneath the soil constitutes an entire ecosystem with microorganisms, insects,...
Good garden soil teems with life and activity. What goes on beneath the soil constitutes an entire ecosystem with microorganisms, insects, and invertebrates. There are good ones and there are others that damage plant roots or emerge to spread disease and eat your lawn, flowers, vegetables, and herbs. Beneficial nematodes can help rid your garden of some common insect pests.
What Are Nematodes?
Nematodes are microscopic worms with highly specialized diets and two kinds are important to gardeners: root-knot nematodes and beneficial nematodes.
Both types are parasitic and thrive in the moist environment surrounding plant roots. The key difference is that root-knot nematodes—Meloidogyne spp—damage plants by invading and corrupting the plant’s root system. Beneficial nematodes—the two most common being Steinernema carpocapsae and Heterorhabditis bacteriophora—are a natural, environmentally friendly method for eradicating soil-born insect pests. These types do not affect humans, animals, or other insects that don’t reside, for at least a portion of their life cycle, below the soil.
Many other types of nematodes are not parasites of plants or insects, instead feeding on fungi, bacteria, and other nematodes. These species help break down organic elements in soil and make nutrients available to plants. Many species are being studied to learn about and understand how they improve and benefit soil.
Beneficial Nematodes for Pest Control
Beneficial nematodes are most commonly used to control insect pests in crops, lawns and gardens, turf, nurseries, citrus, cranberries, and mushrooms.1 A total of five different species are commercially available. Each species targets specific insect pests with some overlap.
Plenty of common garden insect pests live or produce underground. Beneficial nematodes seek out potential hosts by detecting the pest’s chemical signature and destroying them. The lifespan of a beneficial nematode is about two weeks. Here is a sampling of insect pests that have been successfully controlled by beneficial nematodes:
- Cutworms
- Armyworms
- Wireworms
- Fungus gnat
- Japanese beetle
- Common turf grubs
- Black vine weevil
How to Use Nematodes for Pest Control
The most important information when considering applying beneficial nematodes is to make sure the type you select infects the targeted pest. Beneficial nematodes are light and temperature sensitive and less effective in cool or dry environments so investigate the type that works best in your climate.
Beneficial nematodes are effective as pest control only during the third stage of their life cycle. They can be stored for several months at 70 degrees Fahrenheit. How long they can be refrigerated depends on the species. Once they are mixed with water they can’t be stored or saved for future use. Ask your supplier for storage information and expiration date if one isn’t listed.
Beneficial nematodes may come on a sponge, in a gel, granulated, or as liquid. Once the package is opened, use the entire contents. Do not use expired beneficial nematodes which may emit an unpleasant fishy smell.
Follow these steps to apply beneficial nematodes to your lawn, crops, orchards, and gardens:
- Apply beneficial nematodes in early spring or August through September. It’s best to use them as soon as you receive them.
- Morning and evening applications are best.
- Water the application area saturating the top 2 inches of soil.
- Mix the package of nematodes with water according to the instructions.
- Use a watering can, hose with a sprayer attachment, or a mister to disperse the nematode solution.
- Water a second time to move the organisms into the soil.
- Keep soil moist for two weeks.
- Delay reseeding a lawn or planting crops for two weeks following application.
WARNING
Beneficial nematodes can withstand short-term exposure to inorganic products like insecticides and play a part in effective IPM (Integrated Pest Management) strategies for some crops.1 Combining them with other organic practices like crop rotation and companion planting works well for types that don’t tolerate or survive inorganic applications.
Where to Get Beneficial Nematodes
These organic pest controls can be purchased on websites, at garden centers, and at specialty garden retailers. If you’re targeting a specific pest like strawberry borer or cranberry weevil, look for companies with earth-friendly names that offer a range of organic products for the home and garden.
- What is the difference between beneficial nematodes and nematodes?
The biggest difference between beneficial nematodes and others of the more than millions of types is that beneficial nematodes prey on and kill insect pests that spend at least part of their life cycle in the soil.
- How fast do beneficial nematodes work?
Beneficial nematodes begin working rapidly within about 48 hours but it may be two weeks before you see visible results or a reduction in target pest populations.
- What are the disadvantages of nematodes?
Beneficial nematodes are expensive. They have a short shelf life and are sensitive to environmental conditions. Not all types can be paired with inorganic products and several applications may be required to reduce the pest population.