Nematodes are slender, wormlike animals that live in soil, water, and plant tissues. Too small to be seen with the naked eye, they are spread in infested soil on cultivation equipment, in soil moved by water, and on roots of transplants. Bacteria and fungi enter the roots through nematode wounds and cause severe rotting of plant roots. Symptoms include a general stunting, yellowing, loss of vigor, general decline and death. Another indicator is the presence of galls on plant roots which indicate the presence of root-knot nematodes.
Nematodes are least active in winter and most active in summer and early fall.
Thus, late fall and early spring garden crops are seldom damaged seriously unless unusually warm days stimulate nematode activity. The best time to identify a nematode problem is in the summer and early fall. Examine the roots of growing plants for signs of nematode damage at the end of the harvest season. It's best to dig the dig the roots rather than pulling them from the soil. You may need to wash soil from the roots.