The effect of biofumigants on the vegetative growth of five phytophthora species in vitro

Biofumigation refers to the suppression of pathogens and pests by the incorporation of Brassica plants into the soil. In the current study, two biofumigant sources (Brassica juncea and a mixture of two varieties of B. napus) were screened for their effect on the in vitro growth of Phytophthora cinnamomi, P. cactorum, P. citricola, P. cryptogea and P. megasperma. Growth was determined by the measuring dry weight and radial growth of vegetative hyphae. The results demonstrated that B. juncea was superior in its suppressive effect compared to B. napus. There was also significant variation in the sensitivity of the Phytophthora species to the suppressive effects of the biofumigants. P. cinnamomi was the most sensitive species. Where the rates of the biofumigant were sufficient to suppress growth of Phytophthora, the effect was observed to be mostly fungicidal