Nematodes are microscopic worms, often no larger than 0.5-1 mm. They appear in a great variety of species found in both soil and water environments. In the soil, their population density may vary between 2 and 20 million per square meter. A large part of these nematodes feed on the roots of plants and can therefore cause considerable damage in agriculture and horticulture. In general, nematode parasitize on already weakened plants, causing further weakening, deformation and leaf necrosis. This is also referred to as ‘ fatigue’. Nematodes can be the final blow for these plants. Roses are particularly known for this, as are unhealthy trees.
The worst kinds of nematodes live underground. Indications of the presence of cyst nematodes can be ‘sleeping’ plants during the summer season and/or an increase in root growth.
The root knot nematode causes root nodules and root rot . This nematode is also found in tomatoes, lettuce, cucumbers, peppers and eggplants. Roses, Sugar beets, tulips, onions, beans, salsify, carrots, beetroots and strawberries are very sensitive.
The potato cyst nematode is found in potatoes, eggplants and tomatoes. This nematode can cause a severe yield reduction in potatoes. The nematodes penetrate into the root of the potato plant and eats its nutrients, causing the potato plant to either stop growing or die. The abdomen of the female is attached to the outside of the root and expands. When the female nematode dies, about 200 eggs are located in the abdomen. The abdomen containing the eggs is also called a cyst. These cysts remain in the soil after the harvest and may cause infection in following years.
The stem nematode affects many plants. In arable farming, stem nematodes are particularly troublesome in potatoes, alfalfa, rye and onions. Stem nematodes mainly reside in clay soil. They often cause deformations of various parts of plants, sometimes followed by rotting as a result of secondary fungal infections. Stem nematode cause symptoms such as stunted growth and yellow spots in onions. Even low population densities can be harmful. Stem nematodes spread via seeds, bulbs, tubers and rhizomes. Stem nematodes can withstand long period of drought and can therefore survive in the soil for extended periods of time.
Corn Root knot nematodes cause small nodules on the roots and tubers of various crops. The damage mainly translates to a lower quality of the final product.