NVT adopts grower approach to disease management

The results of National Variety Trials (NVT) will more accurately reflect the performance growers can expect from cereal varieties following a change to disease management protocols.

While the GRDC aims to develop and promote disease-resistant varieties, the use of fungicides is seen as an interim response until resistant varieties are available. Wheat NVT trials are sprayed for major diseases such as stripe, stem and leaf rust as required, canola is treated for blackleg, and barley is treated for leaf rust and powdery mildew where necessary.

NVT manager Alan Bedggood says the protocols were expanded in 2012 after first being introduced for stripe rust in 2011.

“We don’t manage for every disease, only those that growers will manage in their own crops,” Mr Bedggood says. “The trial managers will apply fungicides where the need exists, obviously more so in higher-rainfall areas.”

In 2010 the NVT included a number of disease control comparisons in wheat trials; the most severely disease-affected crops showed significant yield differences between those treated for disease and those not treated (see Figure 1).

Mr Bedggood says if the NVT are not treated for disease it misrepresents the potential of some varieties, especially if a commercial variety has become susceptible since its release and is currently widely grown.

“Growers might be getting reasonable results with a variety in the field because they manage for disease but that may not have been reflected in the results of our trials.”

In the case of canola, fungicide seed treatment, which is most commonly used by growers, is not used in the NVT.

“To ensure uniformity of treatments, the NVT program likes to sow all seed bare [untreated], as supplied by the plant breeder, so we use a fertiliser at sowing which has been amended with fungicide,” Mr Bedggood says.

The new disease-management protocols were determined after a review, which investigated the most common disease treatment practices used by growers. The review included feedback from growers, trial managers, pathologists, industry officers, researchers and the GRDC’s advisory committees in each of its agro-ecological zones.

Under the new protocols, the decision to treat for disease, the timing and the application regime is left to the experienced trial operators, in line with treatments being used locally by growers.

Figure 1 Varietal comparisons from the 2010 NVT main season wheat trial at Spring Ridge, NSW
Bar chart showing varietal comparisons from the 2010 NVT main season wheat trial at Spring Ridge, NSW

Varietal comparisons from the 2010 NVT main-season wheat trial at Coolah, NSW, with the error bars indicating the maximum standard error deviation for any combination of varietal yields.Consequently, a lack of overlap of any two error bars indicates a significant difference in yields.

More information:

Alan Bedggood
03 5382 7200
alan@acaslimited.com.au

www.grdc.com.au/GCTV

See the National Variety Trials Ground Cover Supplement for more information.

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