Competition of a sporidesmin-producing Pithomyces strain with a non-toxigenic Pithomyces strain.

Sporidesmin, a mycotoxin produced by some strains of Pithomyces chartarum, is responsible for the hepatogenous photosensitisation disease facial eczema, which causes severe losses in agricultural revenue in New Zealand. A sporidesmin-producing strain of P. chartarum, isolated in New Zealand, was grown in co-culture with a South African strain that does not produce the mycotoxin. Competition occurred between the two strains when grown both on agar plates and on dried ryegrass, with a significant decrease in the total amount of sporidesmin produced. Biological control of toxigenic P. chartarum can thus occur under laboratory conditions, raising the possibility of similar control in the field situation.