Inhibition of in vitro mycelial growth of Sclerotinia sclerotiorum by biofumigant crops

Content Partner: Lincoln University. Sclerotinia sclerotiorum has been identified as a significant pathogen infecting a wide range of plants, including economically important vegetable crops in New Zealand. Biofumigant crops, especially members of the Brassica family, are reported to inhibit the survival, growth and reproduction of many fungi. The present study focused on assessing the biofumigation effect of four selected crops on in vitro mycelial growth of S. sclerotiorum. Four different biofumigant crops, i.e. Brassica juncea (‘Caliente 199’), Brassica juncea (unknown), Eruca sativa (‘Nemat’), Sinapis alba (‘SKU 4295’) were assessed for the inhibitory effect against ten S. sclerotiorum isolates. A sandwich plate assay was set up with 5 g of macerated whole plant tissue, at 50% anthesis stage for each of the selected biofumigant crops, and placed into the inverted lid of a Petri dish containing Potato Dextrose Agar inoculated with a S. sclerotiorum mycelial disc. No contact between the plant tissues and the fungus occurred. Four replicates were set up for each S. sclerotiorum isolate and each biofumigant crop treatment combination, including untreated controls in a completely randomised design. The colony diameter (mm) of each plate was measured until the mycelial growth in the untreated S. sclerotiorum isolate controls reached the edge of the Petri plate (3 days). The inhibitory efficiency (%) of the different treatments calculated by comparing to the mycelial growth in the respective isolate controls. There was a significant effect of treatment and isolate on the inhibition of mycelial growth of S. sclerotiorum (P