Horticulture Australia Limited (HAL) – VG07070: Benchmarking Predictive Models, Nutrients and Irrigation for Management of White Blister. Subcontract Final Report

White blister is caused by the oomycete pathogen Albugo candida and is a common disease of many economically important cruciferous vegetables and oilseed crops. Significant yield losses from this disease have been reported on the oilseeds B. rapa and B. juncea and, to a lesser extent, on susceptible lines of B. napus. Affected vegetables include broccoli, Brussels sprouts, cauliflower, radish, mustard, Chinese cabbage and turnip. The impact of disease in these crops is of a cosmetic nature and can render crops unmarketable. In Australia the disease has been commercially important in vegetable production since 2002

To date, more than ten distinct biological races of A. candida have been identified and classified based on host specificity. The recorded pathotypes in Australia are likely to be Races 1, 2, 3,4, 5, 6, 7, 9 and 10. Race 9 infects B. oleracea and is considered to have caused the recent outbreaks of white blister on broccoli in Australia. Current broccoli varieties tolerant to white blister are not available all year round. Disease management strategies to control the disease include routine spray programs alongside improved irrigation scheduling. In the UK, improved management of the disease and, reduced applications with effectiveness of the fungicides applied, has been achieved utilizing information from an environmental white blister disease risk forecast. This system is currently being trialed in Australia.

The present study aims to improve the environmental white blister disease risk forecast by including information on availability of A. candida airborne disease inoculum. Monoclonal antibodies, with recognition sites to A. candida Race 9 zoosporangia, will be produced and assessed within a PTA ELISA (plate-trapped antibody enzyme-linked immunosorbent laboratory test) for quantification of MTIST trapped field aerosols of A. candida. Preliminary studies will investigate the potential of an immunological chromatographic test strip (lateral flow) to provide ‘in field’ information on A. candida spores in collected field air samples.