Pathogen. The only root-knot nematode that has been detected on potatoes in Ontario is the northern root-knot nematode. Males are worm-like, and females
are pear-shaped.
This nematode causes small galls to develop on the roots, and lateral roots to proliferate around the galls. Brown spots form in the tuber flesh close to the tuber surface.
The spots are visible if a thin layer of tuber is peeled off. The Northern root-knot nematode causes a general swelling of tubers but no warty galls. Penetration of
lenticels results in scab-like lesions.
the northern root-knot nematode.
