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Latest on Canola disease – 2015 GRDC Update papers

Keep up with the latest research information on Canola diseases including BWYV, sclerotinia and blackleg. Below are the take home messages from papers presented at the GRDC Updates in February and March 2015. There were no papers in the Western or Northern regions.

Click the paper titles to view the full papers.

Southern region

Canola disease update 2015 (NSW)

By Kurt Lindbeck (NSW DPI), Stephen Marcroft and Angela Van de Wouw (Marcroft Grains Pathology), Audrey Leo (NSW DPI), Vicki Elliott (Marcroft Grains Pathology) and Barb Howlett (University of Melbourne). Presented at Wagga Wagga, February 2015.

  • Blackleg monitoring sites indicated a slight decrease in the overall blackleg stem canker levels in 2014 compared to 2013.
  • Regional monitoring results for each blackleg resistance group are available on the NVT online website. Consult the Blackleg Management Guide for details of resistance groups.
  • Monitoring canola crops for levels of blackleg is an essential tool when making informed decisions about managing the disease.
  • Symptoms of stem injury due to blackleg were observed higher in the crop canopy in spring 2014, these symptoms caused yield loss in some instances.
  • Sclerotinia stem rot occurred in those districts with a frequent history of the disease. Drier than average conditions in spring kept potential disease levels low.
  • Early sown canola crops in districts prone to sclerotinia stem rot are more likely to develop high levels of the disease.

Canola Disease update 2015 (Victoria)

By Stephen Marcroft and Vicki Elliott (Marcroft Grains Pathology P/L) Angela Van de Wouw (Marcroft Grains Pathology P/L and University of Melbourne) Kurt Lindbeck and Audrey Leo (NSWDPI). Presented at Ballarat, February 2015.

  • Blackleg symptoms have occurred higher in the canopy than previously; these symptoms have caused some yield loss.
  • Blackleg stem canker in 2014 was very low across Victoria except for the North East. This was due to low rainfall.
  • Blackleg pod infection can cause yield loss in some years but was extremely low in 2014.
  • Regional monitoring results for each blackleg resistance group are available on the NVT online website. Consult the Blackleg Management Guide for details of resistance groups.
  • Sclerotinia was almost non-existent in Victoria in 2014 (consistent with low rainfall in spring).
  • Other fungal diseases did not cause any yield losses in 2014 (Alternaria, White Leaf Spot, Downy Mildew, Powdery Mildew, Damping off).

Beet western yellows virus (synonym: Turnip yellows virus) and green peach aphid in canola

By Brenda Coutts (DAFWA), Roger Jones (UWA), Paul Umina (cesar), Jenny Davidson and Greg Baker (SARDI) and Mohammad Aftab (Department of Economic Development). Presented at Adelaide, February 2015.

  • Beet western yellows virus (BWYV, syn. Turnip yellows virus) is widespread throughout grain growing areas of Australia.
  • Early BWYV infection in canola can cause seed yield losses of up to 46%, decrease seed oil content and increase seed erucic acid and glucosinolate contents.
  • Wild radish weeds and volunteer canola are the most important reservoirs but perennials such as lucerne and many weeds species are also infected.
  • Epidemics are likely to occur when aphids are present early in the season (green bridge prior to seeding, warm temperatures).
  • Integrated management strategies have been devised for BWYV in canola.
  • Green peach aphid (GPA), the main vector for BWYV, has a high prevalence of resistance to insecticides. Growers should implement resistance management strategies for insecticides including neonicotinoids.

Virus development in canola crops during 2014 in New South Wales and implications for the oilseed and pulse industry

By Joop van Leur and Kurt Lindbeck (NSW DPI), Mohammad Aftab and Angela Freeman (Department of Economic Development) and Don McCaffery (NSW DPI). Presented at Wagga Wagga, February 2015.

  • Beet western yellows virus (BWYV, syn. Turnip yellows virus, TuYV) was found in most tested canola crops throughout NSW. However, substantial yield losses appeared to be limited to a few paddocks where early infection occurred.
  • BWYV (syn. TuYV) is a persistently transmitted virus that infects a wide range of crops and weeds. Its main vector is the Green Peach Aphid (GPA, Myzus persicae).
  • Virus control strategies should be based on preventing infection as infected plants cannot be cured. Preventive measures to avoid BWYV infection in canola include seed treatment with systemic insecticides that are effective for GPA control and sowing in standing wheat stubble.
  • Growers are advised to check canola crops early in the season for aphid presence and, if found, apply an effective insecticide.
  • There is no indication to date that the occurrence of BWYV (syn. TuYV) in canola poses a threat to neighbouring pulse crops.
  • High infestations of aphid species other than GPA were also observed in other broad acre crops during June-July 2014. Widespread cowpea aphid infections throughout Queensland and NSW resulted in very high levels of infection of Bean yellow mosaic virus (BYMV) in faba bean and, possibly, lupin crops.

Green peach aphids: insecticide resistance, role in the transmission of beet western yellows virus and managing risk in 2015

By Paul Umina, Garry McDonald and Siobhan de Little (cesar). Presented at Wagga Wagga, February 2015.

  • Beet western yellows virus (syn. Turnip yellows virus) is widespread throughout grain growing areas of Australia.
  • The green peach aphid is the main vector of beet western yellows virus.
  • Green peach aphid has a high prevalence of resistance to insecticides.
  • Integrated management strategies have been devised for green peach aphid. These strategies may vary across regions and industries to be most effective.
  • Growers should implement resistance management strategies for insecticides and consider non-chemical management options.
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