Nematodes (nematodes - many species): Affected areas appear yellow and thin, and do not respond to watering or fertilizing. Nematodes feed on turfgrass roots which prevents absorption of water and nutrients. Roots may be stunted, swollen or blackened. Symptoms often are more apparent in hot dry weather because damaged roots cannot take up water fast enough to replace that lost by transpiration. Damage may be more severe in sandy soils.
Management: Care to avoid the introduction of nematodes into the area is the best prevention. Clean all equipment thoroughly. Adequate and properly timed watering reduces the damage caused by nematodes. The effectiveness of fumigant and nonfumigant nematicides depends on the type and texture of the soil. They are most effective on light sandy soils and least effective in heavy clay soils. Heavy watering following the application of nonfumigants is necessary to move the chemical to the root zone. For additional information refer to general section on nematodes and root knot nematode.