GRDC RESEARCH SUMMARY

Decision support systems for forecasting foliar crop diseases and their control strategies

Research summary

• Two well tested models (AnthracnoseTracer and Blackleg Sporacle) have been developed for forecasting the spread of anthracnose disease in lupins and black spot in canola respectively.
  
   
• AnthracnoseTracer can also provide paddock-scale predictions of the risk of loss from lupin anthracnose as part of a seed sample testing service.
  
   
• Blackleg Sporacle has now been run with 10 years weather data for each of the five canola growing areas of South Australia, Western Australia and Victoria and 10 areas of New South Wales. The results are compatible with available observations and illustrate that variability exists in the timing of onset of pseudothecia maturity across the years in all areas.
  
   
• Through Blackleg Sporacle regional, fortnightly forecasts on timing of pseudothecia maturity are provided via PestFax during late summer and autumn to aid planting decisions.
  
   
• A partially tested model (Black spot Appraisal) was also developed and tested for forecasting the spread of blackspot in field peas. This model can also be used to estimate risks of yield loss from this disease.
  
   
• An electronic estimator, called e-Variety Guide for stripe rust, has been developed and distributed widely within WA to assist in the selection of the right wheat variety for managing stripe rust.

Background

The project had three broad aims:

• the production of district-scale forecasting and control strategies for important foliar diseases in crops (anthracnose in lupins and blackleg in canola);
  
   
• production of paddock-scale, practical agronomic control strategies for these diseases; and
  
   
• effective communication of these strategies to growers.

Similar work on black spot in field peas and stripe rust in wheat was also undertaken.

Selected Results

When these models were applied to different scenarios within WA, the following conclusions were made:

Anthracnose in lupins:

• Resistant varieties are the first option to consider for managing this disease in lupins.
  
   
• Crop damage from anthracnose was influenced by the level of initial seed infection. A 0.0025% seed infection would cause ~3% loss whereas 0.05% infection would cause >80% loss in Myallie (1998 season, high rainfall zone).
  
   
• Varietal responses to anthracnose damage are significant. Myallie would suffer ~15% loss whereas Wonga would lose <1% (1998 season, high rainfall zone, 0.01% seed infection).
  
   
• Regional differences are evident for anthracnose damage. With 0.01% initial seed infection, the disease would cause ~15% loss in a high rainfall zone, but similar damage is unlikely in a low rainfall area even with a much higher (1%) level of seed infection (Myallie, 1998 season).
  
   
• Dry weather restricted the spread of anthracnose. The model predicted almost no damage (<1% loss) in a dry season like 2000 whereas 10% damage could occur in a wet year like 1999 (Belara, high rainfall zone, 0.01% seed infection).

Blackleg in canola:

• Blackleg spore maturity and ascospore showers commence early in the southern agricultural region due to cooler and wetter summer and autumn conditions. In the northern agricultural regions, spore maturity is delayed by about two months.
  
   
• Farmers in the northern agricultural region of WA can reduce their disease risk considerably by sowing canola early, to avoid ascospore showers in the susceptible early seedling growth stage. In other regions, delayed sowing may incur yield penalties. The model can be used in the time leading up to seeding to identify seasons where this option will be effective.

Black spot in field pea:

• Maturation of black spot spores commences earlier in the southern than in the northern agricultural regions of WA.
  
   
• Paddock selection can help reduce risks of disease. Peas should be sown as far as possible from where peas were grown in the last two years and preferably be situated upwind.
  
   
• Spore dispersal can occur between properties. This highlights the importance of knowing the cropping history of neighbours’ paddocks before selecting paddocks for growing peas.
  
   
• A two-week delay in planting can considerably reduce the incidence of this disease in the southern regions of WA.

Stripe rust in wheat:

• Choosing the right variety, Wyalkatchem, Carnamah and Datatine instead of traditionally used Westonia, Brookton and Tincurrin, respectively is the first step in managing stripe rust in WA.

Other Information

Diggle AJ, Salam MU, Thomas GJ, Yang HA, O’Connel M, Sweetingham MW (2002). AnthracnoseTracer: A spatio-temporal model for simulating the spread of anthracnose in a lupin field. Phytopathology 92: 1110-1121

Salam MU, Khangura RK, Diggle AJ, Barbetti MJ. (2002). Blackleg Sporacle: A model for predicting onset of pseudothecia maturity and seasonal ascospore showers in relation to blackleg of canola. Phytopathology 93: 1073-1081

Eureka files (summaries of GRDC research projects) are produced by Allan Mayfield and Jon Lamb Communications on behalf of GRDC.

Disclaimer
Any recommendations, suggestions or opinions contained in this publications do not necessarily represent the policy or views of the Grains Research and Development Corporation. No person should act on the basis of the contents of this publication without first obtaining specific, independent professional advice. The Grains Research and Development Corporation will not be liable for any loss, damage, cost or expense incurred or arising by reason of any person using or relying on the information in this publication.

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