Along with soybean cyst nematode, root knot can be diagnosed in the field by the presence of the nematodes on the roots. Root knot produces swellings on the roots of susceptible crops such as cucumbers, cantaloupes, carrots, beans, and many other vegetable crops. At this time of the season the first indication may be some stunting in irregular areas in an infested field. Digging the plants carefully at this time can reveal the swellings on the roots called galls or knots that form around the developing female root knot nematode. Little can be done after galling is seen.
Frequent irrigation can help minimize the damage to the infected root systems.
Check for root knot by soil sampling fields to be planted to susceptible vegetables in the fall before planting the crop. Picture taken from Disease and Pests of Muskmelons and Watermelons, Richard Latin, Extension Specialist Plant Pathology, Purdue Univeristy Cooperative Extension Service, West Lafayette, IN, BP-44 Sweet corn. Common rust is present in some plantings of susceptible sweet corn. If rust is seen before whorl stage, fungicide control may be beneficial. Scouting young sweet corn for rust is highly recommended.