Evaluation of the seed treatment Rancona Dimension as a standalone option for managing crown rot in wheat – 2015

Full description

To determine the impact of Rancona Dimension on yield loss from CR infection across sites in the northern region.
Crown rot, caused predominantly by the fungus Fusarium pseudograminearum is a significant disease of winter cereal crops in the northern NSW and southern Qld. Rancona® Dimension (ipconazole + metalaxyl) was recently registered in Australia as a fungicidal seed treatment with good activity against cereal bunts and smuts, pythium and suppression of rhizoctonia. Rancona® Dimension is also the first seed treatment to be registered (at 320 mL/100 kg seed) for the suppression of crown rot. Suppression by definition indicates that the seed treatment reduces growth of the pathogen for a set period of time early in the season. This is distinct from control which Rancona® Dimension and other seed treatments provide against bunts and smuts of wheat and barley in that they prevent infection throughout the season. It is recommended by the manufacturer that Rancona® Dimension is used as part of an integrated disease management strategy for crown rot and not as a standalone option. However, growers may still be tempted to try and use Rancona® Dimension under medium to high crown rot risk situations where other management strategies have not sufficiently reduced inoculum levels. This is not uncommon following seasons with low in-crop rainfall which limits the effectiveness of break crops such as chickpea, faba bean, canola and sorghum in decomposing cereal stubble which harbours the crown rot fungus. Under this scenario growers are often forced into sowing another winter cereal within the rotation sequence and may be tempted to resort to a seed treatment as their main option in trying to reduce yield loss associated with crown rot infection. Replicated research therefore appeared warranted to determine the impact of Rancona® Dimension on yield loss from crown rot infection across sites in the northern region. This will hopefully ensure that growers have a realistic expectation of what this seed treatment can achieve if used in isolation of other management strategies.