By Josie Borlongan, Garden Guides Contributor

About Nematodes

About Nematodes are soil-dwelling, microscopic, eel-like roundworms that feed on plant roots. The root-knot nematode (Meloidogyne genus) is the most common root-feeding nematode that causes problems for gardeners and farmers. The most serious problems with this group occur in broadleaf plants grown in the warmest and sandiest soils.

Prevention and Control

There are currently no nematicides available for home gardeners. Application of nematicides currently in the market should be accomplished by licensed professionals. Check first with the agricultural commissioner's office if fumigants and nematicides are permitted in your area. Once you get permission, you will need to contact a licensed applicator.
Materials that can be nematicidal include manures, various composts and other organic materials, ammonium forms of nitrogen, sugar and certain salts. Some of these materials are toxic to crop plants, as well as to nematodes.

Affected Plants

Fruits/Trees
Almond
Apple
Apricot
Avocado
Cherry
Citrus
Grapes
Olive
Peach and Nectarine
Pear
Plum and Prune
Walnuts

Vegetables

Asparagus
Beans (black-eye, lima, snap)
Beets
Carrots
Celery
Cole Crops
Corn
Cucumbers
Eggplant
Lettuce
Melons
Onions and garlic
Peas
Peppers
Potatoes (Irish and sweet)
Radish
Spinach
Squash
Tomato
Turnips

Damage

Nematodes can cause damage to infested plants, whereby plants would usually wilt during the hottest part of the day and leaves may yellow slightly. Often fewer and smaller fruits and leaves are produced, and those plants that are highly susceptible may die due to lack of water and nutrients brought about by the damage caused on the roots by the nematodes.

Predator Insects

Fungi
Bacteria
Collembola and other nematodes and soil-dwelling insects

Natural Insecticides

Manures
Various composts
Sugar
Certain salts

Other Methods of Control

* Marigolds and other nematode-suppressive plants
* Soil amendments: Peat, manure, green chop and composts--can be added to the soils to decrease the impact of nematodes on crop plants and increase the ability of soil to hold water that is beneficial to plants.
* Orchard floor management: Cover crops in orchards and vineyards to improve root growth, overall plant health and tree or vine tolerance to nematode damage.
* Planting and harvest dates: Avoid planting or harvesting during summer months when nematodes are most active.
* Sanitation: Avoid movement of soil or water from infested to non-infested areas. However, you can perform a hot water treatment by immersing dormant bulbs or plants in water held at temperature that is high enough to kill the pest without harming the plant.
* Solarizing soil: Covering the soil with plastic during hottest part of summer can kill nematodes.