Sufficiency ranges, however, have not been established for many non-commercial types of plants. Comparing the results from a healthy sample with the results from an unhealthy sample is helpful in situations where ranges are not available or cannot be used. A soil test will also be helpful in diagnosing problem areas. Your Extension agent will help you interpret your results. They can cause substantial damage to plants by feeding on the roots, thus hampering or even destroying the plant s ability to absorb nutrients and water.
Nematodes can also transmit or increase the susceptibility of most plants to diseases and viruses.
As a result of the root damage, plants show symptoms of reduced growth, nutrient deficiency symptoms such as yellowing of foliage, excessive wilting in hot or dry weather, reduced yields, and poor quality yields. Damage often occurs in randomly spaced patches in a field. The only way to positively identify the type and extent of a suspected nematode problem is by soil sampling and a laboratory assay. This should be done before a crop is planted so the grower can choose a resistant variety, a non-host crop, or to apply a nematicide if the assay results indicate a nematode problem. The optimum time to sample summer crops is from July to October.