Nematodes, those microscopic, yet dastardly wormy pests of the garden, usually are known for their damage; gnarled tomato, pepper, corn and potato roots or weakened stems and dying tissues on onions and chrysanthemums. Yet the root knot species responsible for these acts of garden mayhem are the outlaw cousins of the "good" or beneficial species that break down organic matter and enrich the living soil in addition to preying on a smorgasbord of pests from cutworms, thrips and root weevils to earwigs, billbugs and mole crickets.
New Sheriff in Town
Batches of infective beneficial nematodes can be purchased commercially and should be applied when the pest larvae are present in the garden. Dosages and application methods vary according to the pests to be treated and the type of host plant - vegetable, perennial, tree or lawn turf, so as always, read and follow directions carefully, including any safety precautions. Generally, the introduced nematodes will function most effectively when applied in the late afternoon or early evening and well "watered in" to soak them into the soil.
Riding the Range
Preventive methods to avoid nematode infestations in the garden or lawn include rotating crops, (not planting the same plants in the same area year after year), planting non-susceptible cultivars, interspersing a "cover crop" of marigolds, or by solarizing or heating up the moistened soil by covering it with clear plastic during the summer months. This last method requires that the garden area be unused for one warm-weather season although it could be re-planted in the fall of the same year with cool season greens and tubers, or containers could be used during the summer instead of the usual garden plot.
So, although nematodes, like many pests, are extraordinarily hardy, (some included in experiments on the ill-fated shuttle Columbia were found alive amidst the wreckage, after traveling to the edge of space and returning), they can be prevented and controlled with careful planning, a little sweat of the brow and using nature to help in the garden.