Epidemiology of Cauliflower Mosaic virus in South Australia

Abstract

Results are presented of 3 years of aphid trapping and 3 years of surveys of the incidence of infection with cauliflower mosaic virus in Brassica crops at two sites in South Australia. Mosaic infection has been found to be of importance only in cauliflower plantings. The incidence of the disease varied greatly at the two sites, which were located in climatically different regions. In the Adelaide Hills significant spread of the disease occurred only through the autumn months March, April, and May, and in only one of the three years did the incidence of the disease reach epidemic proportions. On the Adelaide Plains spread of the disease occurred throughout the cooler months of the year, from March till September. At both locations increasing incidence of the disease followed increases in the number of trapped aphid vector species. Results indicate that the most important vector in the field is likely to be Brevicoryne brassicae. Trials suggest that seed-bed infection with the virus can be reduced by the use of barrier crops.