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New options on the way for rhizoctonia control in cereals


Australia
June 6, 2014

Source: GRDC Ground Cover

Photo of plant pathologist Daniel Huberli
Plant pathologist Daniel Hüberli examines rihzoctonia trials in the Western Australian wheatbelt. The research, which is being carried out in WA and South Australia, is evaluating the efficacy of new fungicides in controlling the costly pathogen. Photo: DAFWA

Collaborative research between the South Australian Research and Development Institute, the University of South Australia, the Department of Agriculture and Food, Western Australia, and agrichemical companies could result in new banding fungicide options for rhizoctonia control in cereals by 2015

GRDC-funded research in Western Australia and South Australia has shown that liquid banding of a new fungicide increased wheat and barley yields by up to 0.87 tonnes per hectare in a paddock with very high levels of rhizoctonia in the soil before sowing.
The most consistent yield responses resulted when the fungicide was banded simultaneously above the seed on the soil surface behind the press wheel and at the base of the furrow about 3.5 centimetres below the seed.

The Australian Pesticides and Veterinary Medicines Authority is reviewing submissions by Syngenta and Bayer to enable banding of selected fungicides to improve control of rhizoctonia. If approved, registration should be granted by 2015.

Syngenta and Bayer have secured permits to carry out large-scale evaluation of banding fungicides in 2014 – and demonstration paddocks will be on show at local field days across the GRDC growing regions.

Fungicide trials

Research by the South Australian Research and Development Institute (SARDI) and the Department of Agriculture and Food, WA (DAFWA), evaluated banding the Syngenta fungicide Uniform® (registration pending) in wheat and barley for rhizoctonia control.

Yield responses for six treatments of Uniform® are presented in Table 1 for wheat and Table 2 for barley (note: some treatments were evaluated in 2012 and 2013 only). Treatments included: liquid banding of Uniform® as a split application, with half the rate banded on the soil surface and half in-furrow below the seed; applying the fungicide in-furrow below the seed only; and in-furrow below the seed combined with a seed treatment of Vibrance®.

The results are presented as net yield increases (t/ha) for each treatment, with untreated yields (t/ha) and pre-sowing rhizoctonia levels included to help characterise each site. Rhizoctonia field trials are inherently variable and it was difficult to detect statistically significant yield responses of less than 10 per cent.

Disease severity ranged from low to very high in the trials, which used the natural rhizoctonia present in the paddock. Trial sites were selected based on evidence of rhizoctonia in the previous year’s cereal crop and a medium to high level of rhizoctonia DNA (PreDicta B® test) in the soil before sowing.

In wheat, yield responses increased significantly by 0.11 to 0.39t/ha with a medium-rate split application, while at a higher rate the yields were 0.23 to 0.53t/ha higher than the untreated control (Table 1).

For barley there was a 0.2 to 0.69t/ha yield improvement from a medium split rate and 0.37 to 0.87t/ha from the high split rate (Table 2).

Banding fungicide below the seed at the low rate in combination with the seed treatment Vibrance® increased yield significantly in wheat in six of the 11 trials (Table 1) and in barley in four of the 10 trials (Table 2).

Seed fungicide treatment alone increased yields significantly in only three (Karoonda, SA; Lake Grace, WA; Minnipa, SA) of the 11 wheat trials (Table 1) and one (Lameroo, SA) of the 10 barley trials (Table 2).

In the SA trials, the surface application treatment applied behind the press wheel was using a low-volume, narrow-angle nozzle set to spray along its narrow side creating a narrow band about 2cm wide.

In WA, the surface band treatment was applied as a trickle in a separate pass following the first-pass application of fungicide as a trickle below the seed using GPS-controlled auto-steer.

View complete article with tables


Integrated management of rhizoctonia

  • Fungicides should be used as part of an integrated management approach for rhizoctonia.
  • Factors that lower the disease risk of rhizoctonia include:
  • rotating cereals with canola to lower rhizoctonia inoculum;
  • controlling the autumn green bridge, which can host rhizoctonia;
  • sowing early within the optimum sowing window and disturbing the soil at least 10 centimetres below the seed to encourage rapid root growth down the soil profile;
  • applying seed treatments (yield responses average about five per cent);
  • increasing seeding rate to reduce impact of lost tillers from rhizoctonia damage to crown roots;
  • encouraging high seedling vigour by applying adequate nutrition – especially nitrogen – and not incorporating stubble (which can increase risk of nitrogen deficiency);
  • addressing in-crop nutrient and trace element deficiencies with foliar applications; and
  • using knifepoint soil openers rather than discs to sow crop.


More solutions from: GRDC (Grains Research & Development Corporation)


Website: http://www.grdc.com.au

Published: July 10, 2014

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


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