Root knot nematode – Meloidogyne spp., nematode
Root knot nematode is a relatively minor pest of potato in the Northeast. Infection of tubers by the root knot nematode often results in the formation of galls that appear as knobs or swellings on the tuber surface. These are somewhat similar in appearance to tuber malformation due to uneven growth. This symptom occurs when tubers are infected by relatively high nematode populations. If shallow cuts are made through the malformed tissues, the white swollen bodies of the female nematodes will be visible. Surrounding tissues will appear somewhat water soaked, and necrotic flecks may be present. However, when nematode populations are low, infection does not always result in swelling of the tuber surface, and the only symptom may be small necrotic flecks in the cortex of the tuber where the nematodes have penetrated. Identification of the species of root knot nematode can only be done through a nematode diagnostic service. Nematodes can survive in potato tubers and be a source of inoculum when infected tubers are used for seed.