Pathology and histopathology of Pratylenchus scribneri infecting snap bean and lima bean

The pathological effects of Pratylenchus scribneri on susceptible snap bean and resistant lima bean were studied. In a pathogenicity test, the nematode increased nearly 75-fold on snap bean and suppressed top growth. On lima bean, P. scribneri reproduced slowly and did not significantly affect top growth. Discreet lesions formed on lima bean roots, but no lesions developed on snap bean roots. Paraffin sections taken 2, 5, 13, 25, and 32 days after inoculation showed little cellular necrosis in snap bean roots, whereas cells surrounding the nematode in lima bean were extensively necrotic. Cortical cells of infected snap bean roots were almost completely invaded and killed 25 and 32 days after inoculation. The cortex of lima bean tissues was intact, although localized necrotic areas remained at sites of nematode invasion.