Plant Pathology: Extension: Plant Disease Library

Cylindrocladium (Calonectria)

Important diseases: Cylindrocladium black rot (CBR) of peanut, root rot and leaf spot of azalea and leaf spot of holly

Cylindrocladium causes root rots, crown and lower stem blights, and leaf spots. The fungus affects legume field crops, ornamentals, and forest and shade trees. A black discoloration and necrosis of roots and lower stems ae typical symptoms.

Cylindrocladium causes necrosis and black discoloration of the root system. Infection may spread into the crown and lower stem. Cylindrocladium conidia may be observed on infected crown or lower stem tissue. Reddish-orange perithecia (fungal fruiting structure) of the sexual stage of Cylindrocladium, Calonectria, also may be observed on infected lower stem and crown tissue.

Conidiophores are colorless and highly branched. Conidia are produced at the apex of conidiophore branches. Masses of conidia appear white and often are arranged in a circular, closely packed pattern.

Cylindrocladium conidia are colorless (hyaline), slender, elongate, and two celled. The cross wall (septum) is located directly in the middle of the spore.