Necrotrophic

Necrotrophic describes a mode of nutrition and interaction in which an organism derives nutrients from dead or decaying tissue. In plant pathology, necrotrophic pathogens cause host tissue death (necrosis) and then feed on the dead material. This contrasts with biotrophs, which feed on living tissue, and with hemibiotrophs, which begin as biotrophs and later switch to necrotrophy.

Mechanisms often involve production of cell wall–degrading enzymes and phytotoxins that kill plant cells, followed by colonization of the dead tissue. Some necrotrophs secrete necrotic effectors that disrupt plant metabolism and induce cell death. They typically spread rapidly through soft tissues and form conidiophores, sclerotia, or other reproductive structures on necrotic tissue.

Common plant necrotrophs include Botrytis cinerea (gray mold) and Sclerotinia sclerotiorum (white mold), as well as Rhizoctonia solani and various Fusarium species. Mechanisms and aggressiveness vary by species, host, and environment; temperature, humidity, and plant defenses influence infection. Management emphasizes reducing tissue susceptibility, crop rotation, sanitation, resistant cultivars, and fungicide programs; breeding for resistance against necrotrophs focuses on strengthening basal defenses and tolerance to toxins rather than preventing pathogen ingress alone.