Broad disease constraint resources are outlined in the Agronomists Toolkit. Specific disease categories are listed below:



Constraint - Blackleg


  • Blackleg is the most serious disease of canola in Australia

  • Blackleg is caused by the fungus Leptosphaeria maculans

  • The severity of blackleg has risen in recent years due to increased acreage and intensity of production


  •  The first sign of infection are off-white lesions forming on leaf tissue

  • Once a lesion has formed, the fungus grows within the plants vascular system to the crown where it causes the crown of the plant to rot, resulting in a canker

  • Severe canker will sever the roots from the stem, whereas a less severe infection will result in  restriction of water and nutrient flows within the plant

  • In recent years blackleg symptoms have also been found in the plant roots, this root infection in severe cases appears to cause the entire plant to die prematurely


  • Although not common, yield losses of 50 per cent and greater have been recorded 

  • Up to 90 per cent yield loss had occured in cases where blackleg has overcome major resistance genes within certain varieties


Blackleg can be succcesfully managed by growing resistant varieties, isolating the current crop from infected stubble by up to 500 metres, and using fungicides as seed dressings or in fertiliser in high risk situations. 

Links and Resources

AOF - Blackleg warning fact sheet

Information on high risk blackleg indicators, recommendations for growers in high risk situations, susceptible varieties, overcoming resistance, and how to monitor blackleg severity. Published 2009.

AOF - Burning canola stubble may not control blackleg

2 page document on burning stubble to control blackleg in canola. Contains detailed information and trail results. Published 2007.

DAFWA - Managing blackleg

4 page PDF. Summary, introduction, seedling infection, integrated management, varietal response, minimising risk of spore showers, disease pressure categories, and using impact. Published 2003.

DEPI VIC - Blackleg of Canola

Introduction, symptoms and disease cycle, and management. Published 2008, updated 2009, reviewed 2010. Page last updated 2013.

GRDC - Best Practice Management Guide. Blackleg

Page 59. Common diseases of canola table, blackleg is referenced. Introduction, symptoms, disease cycle, table of resistance ratings, and management. Published 2009.

GRDC - Blackleg management fact sheet

4 page PDF. Key points, risk, severity, management practices, resistance groups, and monitoring. Revised 2013.

PDF GRDC - Over the bar with better Canola agronomy. Blackleg

Trial on pages 11 and 12 on the effect of Jockey on yield in blackleg prone areas.Trial on pages 13 and 14 on blackleg disease in Lower Eyre Peninsula canola crops. Pages 15 and 16 Managing blackleg in canola including risk indicators, recommendations, and disease ratings. Published 2010.

File size: 1.9mb
Victorian winter crop summary 2014 - Blackleg

Page 45. Table 1: canola disease guide summary. Description of organism, symptoms, occurrence, inoculum source, and control. Updated annually.

File size: 1.9mb