Occasionally plants infested with Columbia root knot nematode will have egg masses, which appear as tiny bumps, on the root surface. Plants heavily infested with barley root knot nematode may be stunted, chlorotic, and often fail to develop heads. Plants infested by lesion nematode, Pratylenchus thornei, will be stunted and yellow in patches, have brown leaf tips, fewer tillers and smaller heads. Stem and bulb nematodes can curl newly emerging leaves into spirals, stunt plants, reduce tillering, inhibit head formation, and sometimes kill the plant. The cereal cyst nematode has been found on grasses in some parts of California, but not on small grains.
Infested roots are short, and abnormally branched.
To make management decisions, it is important to know the nematode species present and their population estimates. If a previous crop had problems caused by nematodes that are also listed as pests of small grains, population levels may be high enough to cause damage to subsequent crops. If nematode species have not previously been identified, soil samples should be taken and sent to a diagnostic laboratory for identification. Soon after harvest or preferably just before harvest take soil samples from within the root zone of the previous crop. Divide the field into sampling blocks of not more than twenty acres each that represent cropping history, crop injury, or soil texture.