New fungicides to tackle Rhizoctonia in Australia

A team of researchers from the South Australian Research and Development Institute (SARDI), the University of SA and CSIRO is assessing the use of new fungicides to reduce yield losses caused by Rhizoctonia solani AG8.

The work is being funded by the GRDC and the South Australian Grain Industry Trust (SAGIT), with similar trials also being conducted in Western Australia by the Department of Agriculture and Food, WA.

The trials in both states have included Vibrance® and EverGol® Prime, which have been registered for use as seed treatments in 2013 to lessen Rhizoctonia damage.

SARDI’s Dr Paul Bogacki says: “In SA and WA field trials over the past two seasons, seed treatments with these newly registered fungicides have produced yield responses in wheat and barley averaging about five per cent.

“It is anticipated that these products will be most effective in paddocks with low to moderate levels of Rhizoctonia.”

The recent studies have greatly increased researchers’ understanding of Rhizoctonia. CSIRO trial results show Rhizoctonia can attack crops throughout the growing season and not just seedlings, as previously thought. 

Research has also found that cereals and grasses are the main hosts and crops such as canola (grass-free) can provide useful reductions in inoculum levels, which can benefit the following crop.

The projects will run for one more year to see if banding fungicides can provide additional yield responses, and to generate data to support label recommendations and complete studies on the role of summer weeds.

Advisers say fungicides should be used as part of an integrated management package for Rhizoctonia control. Other good agronomic practices, such as crop rotation, balanced nutrition, grass weed control, furrow disturbance at seeding and seed placement depth, would still need to be maintained.

Effective control of Rhizoctonia:

Dr Alan McKay from the South Australian Research and Development Institute (SARDI) reminds growers why Rhizoctonia is so difficult to control.

Risk of Rhizoctonia is likely to be high in 2013 if the lack of rain in summer/autumn continues, following the dry spring in 2012. Risk will be even greater for crops with slow early root growth caused by cold soil, low nitrogen and compaction layers.

Research results indicate the risk of Rhizoctonia damage will be reduced for:

• cereals following grass-free canola, pulses and pastures;
• crops with rapid early root growth down the soil profile – consider sowing early with soil disturbance below the seed, deep band nitrogen and new fungicide     seed dressings; and
• registered fungicide seed dressings used in paddocks with low to moderate levels of Rhizoctonia