Brassica green manure rotation crops reduce potato stem rot caused by Sclerotinia sclerotium

This study was conducted to evaluate the potential of biofumigation in three Brassica crops including Brassica napus , Brassica juncea and Brassica campestris against potato stem rot caused by Sclerotinia sclerotiorum in field tests. Results from field trials carried out in three naturally infected potato fields during three cropping seasons of 2008–2010 showed that the Brassica crops used as green manure cover crops were able to significantly reduce disease incidence and mean percentage of dead plants (as a proportion of infected plants). Although results varied somewhat by field site and year, B. juncea generally provided the highest level of control, averaging greater than 55.6 % reduction in disease incidence over all fields and years, compared to average disease reductions of 31.6 and 45.8 % for the B. napus and B. campestris crop treatments, respectively. Furthermore reduction of dead plants averaged 61.6, 39.2 and 32.1 % for B. juncea , B. napus , and B. campestris , respectively. In this study, Brassica crops showed various significant inhibitory effects in different fields and years indicating that disease development is affected by other factors including environmental conditions.