No bulb and stem nematode symptoms on either carrot or onion were observed in the fields sampled, but damage from this plant parasitic nematode can devastate yield and quality. Figure 1 . Young onion plants infected with bulb and stem nematode. Severely infected plants eventually turn yellow and die. Symptoms frequently look similar to damage caused by onion maggot.
Infected bulbs are also very susceptible to secondary infections by bacteria and fungi.
Figure 2 . The outer layers of scales of the infected bulbs are split allowing the inner layers to bulge through. When the splits extend into the root region, leaf-like shoots often grow out where roots normally grow. Although strains of the bulb and stem nematode that infect carrots have not been confirmed in Ontario, growers should become familiar with the damage symptoms. Young carrot seedlings develop distorted leaves and by harvest time, infected crowns become spongy and crumbly making mechanical harvesting difficult.