Disease-resistant varieties provide the first line of defence against many important pulse diseases.

A new national pulse disease rating system has been implemented to provide consistent and independent disease ratings across the country, following the expansion of GRDC’s National Variety Trials (NVT) disease-rating program to pulse crops in 2019.

The independent disease ratings for pulses (Table 1) were developed using processes adapted from those established and proven for wheat and barley.

Table 1: The crops and diseases included in the new National Variety Trials screening that commenced during 2019, and the states where they will be screened.

Source: Dr Joshua Fanning

Disease ratings

The definitions for each pulse disease rating category have been updated to reflect the appropriate disease management strategy, which is more informative for growers and advisers.

There may be some changes to the previous pulse disease ratings in the update, but there will be better alignment between crops and diseases nationally.

Key rating definitions include:

• resistant (R): No symptoms are visible and no fungicides are required;
• moderately resistant (MR): The disease may be visible but will not cause significant plant damage or loss. However, under high disease pressure or highly favourable environments or conditions, fungicide applications may be required, for example to prevent seed staining;
• moderately resistant to moderately susceptible (MRMS): The disease symptoms are moderate and may cause some yield and/or seed quality losses in conducive conditions. Fungicide applications, if applicable, may be required to prevent yield loss and seed staining;
• moderately susceptible (MS): Disease symptoms are moderate to severe and will cause significant yield and seed quality loss in the absence of fungicides in conducive seasons, but not complete crop loss; and
• susceptible (S): The disease is severe and will cause significant yield and seed quality loss, including complete crop loss in the absence of fungicides, in conducive conditions.

Screening process

Each year 51 disease screenings are conducted across Australia by plant pathologists. These are done in either the field and/or glasshouse to maximise disease expression. In glasshouse conditions, industry-relevant isolates are chosen to infect test plants.

Changes in pathogenicity (harmfulness) for some diseases are regularly monitored through separate GRDC investments, and this information influences the choice of isolate used in the NVT tests. This ensures a field-relevant disease rating is obtained.

Due to shifts in the pathogenicity, it is important that growers use up-to-date variety ratings to make variety and disease management decisions appropriate for their situation.

At the end of the season, data collected nationally via the NVT program is collated and disease ratings assigned by experts for each disease. The disease ratings are updated annually and made available in state-based disease guides and on the NVT website.

This information can lead to a change in variety selection where disease risk is high, and it will support effective disease management decisions for the selected variety.

More information: Dr Joshua Fanning, 0419 272 075, joshua.fanning@agriculture.vic.gov.au; Dr Jenny Davidson, 08 8429 2228, jenny.davidson@sa.gov.au; Jason Sheedy, 07 46311185, jason.sheedy@usq.edu.au; Kurt Lindbeck, 02 6938 1608, kurt.lindbeck@dpi.nsw.gov.au; Geoff Thomas, 08 9368 3262, geoff.j.thomas@dpird.wa.gov.au; NVT disease ratings for pulses; Disease rating definitions