The potential of Ascochyta caulina as a biological control agent for Chenopodium album in organic production

Application of Ascochyta caulina to Chenopodium album plants resulted in hi gh levels of infection and leaf necrosis at high relative humidity. Biologi cal control of C. album by A. caulina was more effective when the spores we re applied in nutrient rich media (V-8 vegetable juice). Prolonged high hum idity (r.h.> 95% for 20 hours after inoculation) and plant growth stage (pl ants must be younger than 4 leaf stage) at time of spore application are cr itical for successful biological control. High nitrogen levels in the plant were shown to favour high levels of infection in C. album.