Symptoms Common symptoms of nematode injury to turf are slight to severe yellowing of the foliage, thinning of the turf canopy, reduced growth, wilting under light moisture stress, and premature death. The foliar symptoms of nematode injury on turf are similar to those caused by low fertility, root-feeding insects, soil compaction, drought stress, and other sources of stress to turfgrass root systems. Because nematodes are unevenly distributed in the soil, patches of injured turf vary greatly in size and shape. The margin between the healthy and nematode-damaged turf is gradual, not sharp. Poor response to irrigation, fertilizers, or fungicide applications is often an indication of a nematode problem.
Damaged turf is generally unable to withstand severe heat or even mild drought stress.
Symptoms of nematode damage usually do not appear until injury to the turf root system is well advanced. Nematode damaged roots are often discolored, short, and stubby with few feeder roots. The diagnosis of nematode injury based solely on the non-specific foliar symptoms is usually quite difficult, if not impossible. The affected turf must be carefully examined to eliminate other possible causes of turf decline. An accurate diagnosis of a nematode problem, however, can only be made on the basis of an analysis of soil from the damaged area to determine the kinds and numbers of plant parasitic nematodes.