Root knot nematode
Description: Worm-shaped parasite that is invisible to the naked eye
Timing of damage: When soil temperatures reach 60°F to 65°F and continue to develop as long as soil temperatures remain above 50°F
Type of damage: Plants will appear stunted, wilted or yellowed, or they will be dead. Roots of infected plants will appear swollen or knotted.
Scouting: Dig stunted plants from the edge of the infected area and check for root galls. Take a soil sample from the root zone and send it to a nematology lab; be sure to keep the soil in the shade to avoid high temperatures.
Economic threshold: Varies with soil type. Ask nematology lab or local Extension office for guidelines.