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Latest in Canola disease – 2019 GRDC update papers

Blackleg lesions in canola

Keep up with the latest research information on Blackleg, Sclerotinia and Turnip Yellows Virus. The following papers were presented at the GRDC Updates across Australia in February and March 2019 and August 2018. The papers are sorted by region. Click the paper titles to view the full papers.

Southern region
Western region

We’ve also pulled together all the:

Pulse disease papers
Cereal disease papers

Canola – What Disease Is That And Should I Apply A Fungicide?

Authors: Susie Sprague (CSIRO Agriculture & Food), Steve Marcroft (Marcroft Grains Pathology), Angela van de Wouw (University of Melbourne), Andrew Ware (SARDI) and Kurt Lindbeck (NSW DPI)

  • Disease symptoms on canola are caused by a variety of pathogens. Correct identification is critical to ensure appropriate control strategies are selected. Use the GRDC Back Pocket guide for Canola: the ute guide, for disease identification.
  • Blackleg and sclerotinia stem rot most commonly cause significant yield loss. Whilst other diseases can be common and prevalent, the level of yield loss associated with other disease infection is either low or has not been quantified.
  • Blackleg crown canker results from infection during early seedling growth. Prior to sowing, use the BlacklegCM decision support tool to identify high risk paddocks and explore management strategies to reduce yield loss.
  • Blackleg upper canopy infection is the collective term for flower, peduncle, pod, main stem and branch infection, but does not include crown canker.
  • Upper canopy infection can cause yield losses of up to 30%. Yield loss is reduced by selecting cultivars with effective major gene resistance and using crop management strategies to delay the commencement of flowering to later in the growing season, especially in high disease risk areas.
  • Sclerotinia stem rot in high risk situations can be controlled by fungicide application at 30% bloom (14-20 flowers on main raceme).
  • Foliar fungicide application for sclerotinia control (approximately 30% bloom) can reduce UCI if it is present and causing yield loss. Unfortunately, applications during flowering do not protect the pods from pod lesions. More work is required to determine robust foliar fungicide timings and economic returns.
  • Blackleg pathogen populations with resistance to the triazole fungicides fluquinconazole, flutrial and a tebuconazole + priothioconazole mixture have been detected. No resistance was detected for new succinate dehydrogenase inhibitor (SDHI) and quinine-outside inhibitor (QoI) chemistries.

Viruses In Spring-Sown Dual-Purpose Canola In The High Rainfall Zone Of Southern Victoria

Authors: Frank Henry and Mohammad Aftab (Agriculture Victoria)

  • Spring-sown canola provides a virus reservoir for Turnip yellows virus (formerly Beet western yellows virus), Cauliflower mosaic virus and Turnip mosaic virus.
  • There is a high risk of transmission of Turnip yellows virus from spring- to autumn-sown canola under favourable conditions.
  • There is a need to manage Turnip yellows virus in spring-sown canola and protect autumn-sown canola from transmission of the virus by aphids.

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Turnip Yellows Virus Epidemic In 2018 – Time To Get One Step Ahead Of The Green Peach Aphid

Authors: B. Congdon, P. Matson, F. Begum, T. Dore, M. Kehoe and B. Coutts (DPIRD)

  • In 2018, severe Turnip yellows virus (TuYV) epidemics in pre-flowering canola crops were caused by early green-peach aphid (GPA) incursions and infestation. Such epidemics are likely to become more frequent due to earlier sowing times, high susceptibility of current commercial varieties, and variable efficacy of neonicotinoid seed dressing.
  • For such epidemics, an early warning system was developed using an innovative molecular diagnostic protocol to detect TuYV in migrating aphids caught on sticky traps. This provides TuYV detection before it reaches high incidences in the crop allowing growers to make targeted applications of systemic insecticide (e.g. sulfoxaflor) to give effective green peach aphid control thereby preventing epidemics and subsequent seed yield and quality losses.
  • In 2019, DPIRD will supply yellow sticky traps prior to the growing season and offer free testing to interested agronomists and growers, whilst continuing surveillance at various south-coast locations.

Tailored Management Of Sclerotinia In Canola With The SclerotiniaCM App

Authors: Art Diggle (DPIRD), Steve Marcroft (Marcroft Grains Pathology), Kurt Lindbeck (NSW DPI), Ravjit Khangura (DPIRD), Audrey Leo (NSW DPI), Ciara Beard (DPIRD), Andrea Hills (DPIRD), Angela van de Wouw (University of Melbourne), Andrew Ware (SARDI), Susie Sprague (CSIRO, Agriculture and Food) and Jean Galloway (DPIRD)

  • The app will support users to make the most profitable decisions about fungicide use to manage Sclerotinia stem rot in canola.
  • SclerotiniaCM is designed for quick and efficient use with clients in the field.
  • SclerotiniaCM produces results that are tailored for individual paddocks and generates email reports right from the field.

Validating The SclerotiniaCM App For Managing Sclerotinia In Canola

Authors: Bonnie Jupp, Alice Butler, Ciara Beard, Anne Smith, Laurie Wahlsten, Bec Swift and Jean Galloway, DPIRD

  • SclerotiniaCM is an app to aid growers and consultants in making economic fungicide application decisions to manage Sclerotinia in canola. Petal testing, fungicide trials and sclerote germination monitoring were used to validate the SclerotiniaCM app which was undergoing testing in the 2018 season.  The app is due for release in 2019.
  • The South Coast experienced a drier start to 2018 and this produced patchy emergence of canola as well as delayed apothecia germination (late August) and  disease development. In contrast, most of the Geraldton Port Zone experienced periods of constant moisture from July to early September and thus highly conducive conditions for apothecia germination (mid-July) and crop disease development. The SclerotiniaCM app correctly identified the value of applying a fungicide spray in trials and large-scale demonstrations in commercial crops in the Geraldton port zone while suggesting spraying would not be worthwhile on the south coast.
  • Apothecia observations, petal infection, disease progress and yield results from both the Geraldton and Albany port zones confirmed the SclerotiniaCM app offers an easy and useful tool for making decisions on whether or not to apply fungicide for Sclerotinia management.

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