Sclerotinia stem rot

Constraint - Sclerotinia stem rot

Description

• Sclerotinia stem rot is caused by the fungus Sclerotinia sclerotiorum

• The disease is sporadic, occurring when environmental conditions are favourable

• Prolonged humid conditions during the flowering period favour disease development

Symptoms

• Light brown discoloured patches develop on stems, branches and pods, which then expand and turn greyish-white

• Infected canola plants ripen earlier and stand out as bleached or greyish coloured plants 

• When an infected canola stem is split open, hard black bodies called sclerotia can usually be found inside

• In wet or humid weather, a white growth resembling cotton wool can develop on lesions and sclerotia may also develop in this white growth

Damage

• Yield losses as high as 24 per cent have been recorded in Australia

Management

Yield losses in  crops can be reduced by the timely application of fungicides during flowering. Using good quality seed clean seed, implementing a three to four year rotation, controlling broad leaf weeds, and maintaining a disease break of at least 200 metres between affected canola stubble and a new canola crop are all management strategies that can help to reduce the risk of an outbreak.

Links and Resources

CAA - Managing Sclerotinia stem rot in Canola 4 page PDF. Summary, introduction, life cycle and symptoms, sclerotinia prone regions and incidence, warning signs, management options, what doesn’t work, estimating yield loss, and future research. Published 2008.

DAFWA - Diagnosing Sclerotinia in Canola Introduction, symptoms, assessment of risk, management of sclerotinia, rotation, tillage, fungicide timing, incidence in WA, variety resistance, effectiveness of fungicides, and conclusion. Page last updated 2014.

DEPI VIC - Canola diseases. Sclerotinia stem rot The section on sclerotinia stem rot contains introduction, symptoms, disease cycle, and management. Published 2008, page last updated 2009, and reviewed 2010.

DEPI VIC - Identification and management of field crop diseases in Victoria. Sclerotinia Page 146. Table 11.1 gives a key for canola diseases at different stages of plant growth. Pages 148-150. Introduction, symptoms, disease cycle, warning signs, and management. Published 2012.

GRDC Best Practice Management Guide - Sclerotinia stem rot Page 62. Introduction, symptoms, disease cycle, and management.  Page 59. Table of common disease of canola. Published 2009.

Victorian winter crop summary 2014 - Sclerotinia Page 45. Table 1: Canola disease guide summary. Description of organism, symptoms, occurrence, inoculum source, and control. Updated annually.