Cell necrosis of localized areas is induced by

Cell necrosis of localized areas is induced by Helicotylenchus.
Helicotylenchus is a genus of nematodes in the family Hoplolaimidae. They are known generally as spiral nematodes.
Helicotylenchus multicinctus causes small necrotic lesions on roots, and with heavy infestation these lesions coalesce, leading to root necrosis and die-back of roots. Plant stunting and reduction in yield. It can cause enough root necrosis that it seriously weakens the plant.