VG00044 Clubroot – Chemical control

Clubroot is the most serious soilborne disease affecting brassicas world wide.

Clubroot is caused by Plasmodiophora brassicae Woronin, an obligate biotrophic parasite.

Australian crop losses are estimated at between 5 and 10% of production.

Clubroot is endemic in most of the major production regions of Victoria, New South Wales and
Tasmania.

FACT :  Well applied chemicals can control Clubroot
on heavily infested sites

Chemical application may be necessary on high risk soils to achieve adequate control of clubroot.

Fungicides

• In 2005, the registered chemicals for suppression of clubroot on cruciferous crops include PCNB (Terraclor®, Barmac Chloroturf®, Barmac Chloroturf DG® Purasoil®) and Fluazinam (Shirlan®).
• These products are most effective when applied at transplanting into the plant root zone.
• Drench applications don’t sufficiently penetrate the soil to provide adequate protection.

Strategic application:

• In trials, control of clubroot was optimised by incorporation of fluazinam into the transplant row at a rate of 3L product (Shirlan® 50% a.i.)/ha in 500L/ha of water immediately before transplanting.
• A number of machines have been developed that incorporate chemicals into the transplant row immediately before planting. This cut costs substantially as only 1/3 of the lane is treated and ensures that the products are in exactly the right place for early crop protection.

Fumigation

• A properly applied soil fumigant gives good disease control acting as a general biocide.
• Metham sodium and Dazomet (Basamid®) have registration for use on soils for food crops.
• Fumigation is expensive and is not recommended as a routine practice because of potential effects on soil structure and biology.

Acknowlegements:
Financial support for this research has been provided by: Horticulture Australia Limited, the vegetable
growers R&D levy and Stae Departments of Agriculture.

Thanks to the following growers for their assistance with trial work:

Thanks to the following for their technical assistance on the project:

Statistical advice by Fiona Thomson and Nam Ky Nguyen (Department of Primary Industries, Vic).