Integrated control of onion white rot on spring onions using diallyl disulphide, fungicides and biocontrols.

摘要

Six field trials evaluated different methods of controlling onion white rot (OWR) on spring onions grown for 12-14 weeks in sandy soils naturally infested with sclerotia of Sclerotium cepivorum. The standard fungicide procymidone, applied using a variety of methods, did not provide satisfactory control of OWR at high disease sites. In contrast, the fungicides boscalid and tebuconazole provided very effective control of OWR. The fungicides azoxystrobin and triadimenol were also identified as having potential for OWR control on spring onions. Synthetic DADS (78% diallyl disulphide), injected into soil before growing spring onions, was very effective in reducing the population of sclerotia in soil and OWR incidence. Two applications of DADS at 5 or 10 L per ha were more effective than one application for reducing OWR incidence. Control of OWR was more effective when DADS was integrated with fungicide (boscalid). The biological control agent Trichoderma atroviride (C52) was more effective at reducing disease incidence under low than high disease pressure conditions. The information collected has enabled the development of an integrated strategy for the control of OWR on spring onions. The new control measures and integrated strategy are discussed.