Fungicide timing for control and yield loss from sclerotinia sclerotiorum in canola 2014 trial report

Page last updated: Wednesday, 25 July 2018 - 11:36am

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For successful management of sclerotinia stem rot in most years it is critical to target fungicides at early stage of bloom (20-30%), but optimal timing can vary depending on the season, in particular the regularity and quantity of rainfall that falls during crop flowering which is when infection occurs. There is a need for growers to be flexible with fungicide application depending on the season. These trials compare 'standard’ recommended timing with a flexible timing approach for minimising yield loss from sclerotinia stem rot in canola in the northern agricultural region.

Background

Sclerotinia stem rot has become one of the major problems affecting canola crops in recent years, particularly in the Northern region of Western Australia.

There is great demand from industry for further information to be gathered on potential yield loss and also risk of yield loss occurring.

For successful management of sclerotinia stem rot, in most years it is critical to target fungicides at early stage of bloom (20-30%), but optimal timing can vary depending on the season.

In 2013, for example, when infection was delayed due to dry June and then followed by a particularly wet spring, late fungicide application, at or even past 50% bloom gave a good yield response.

There is a need for growers to be flexible with fungicide application depending on the season.

With the aid of a sclerotinia forecasting model that is currently being constructed we hope to be able to estimate the risk of sclerotinia in a given year and predict the best time of fungicide application that will reduce yield loss.

This involves considering air temperature, soil temperature, rainfall and flowering stage.

Aims

To compare fungicide application at the ‘standard’ recommended timing with a flexible timing approach based on epidemiology/model disease risk forecasting for minimising yield loss from sclerotinia stem rot in canola.
To gather yield loss due to sclerotinia data.

Trial details

Similar trials were conducted at four locations in the northern agricultural region.

Arrino trial

Table 1 Trial details, Arrino trial
Property	Gary Cosgrove, Arrino
Crop/variety	Canola - 404
Treatments	Nil Fungicide application at 20-30% bloom (Prosaro® at 450ml/ha) Full control – fungicide application at 5% bloom + fungicide application at 40% bloom
Replicates	Four

Arrino results

Disease was not observed at the site so the trial was discontinued.

Strawberry trial

Table 2 Trial details, Strawberry trial
Property	Daniel Michael, Strawberry (Mingenew)
Crop/variety	Canola
Treatments	Nil Fungicide application at 20-30% bloom (Prosaro® at 450ml/ha) Aviator fungicide application at 20-30% bloom
Replicates	Four

Strawberry results

Stem infection has been observed at the site since August and appears to be more common in the nil treatments. A thorough disease assessment has been done in September. Disease observations and yield results will be provided when they are available.

Sclerotinia stem rot infection on canola leaf in the Strawberry trial in 2014

Sclerotinia stem rot infection on canola stem in the Strawberry trial in 2014

East Chapman trial

Table 3 Trial details, East Chapman trial
Property	EF Smart and Co, East Chapman
Crop/variety	Canola - 404
Treatments	Nil Fungicide application at 20-30% bloom (Prosaro® at 450ml/ha) Flexible fungicide application at 40% bloom (Prosaro® at 450ml/ha) Full control - spray (treatment) 2 + spray (treatment) 3
Replicates	Four

Disease assessments being done at East Chapman sclerotinia fungicide timing trial in 2014

Sclerotinia stem rot infection a canola stem in the East Chapman trial in 2014

East Chapman results

Leaf infection was present from July and stem infection has been observed at the site since August and is more common in the nil treatments. A thorough disease assessment has been done in September. Disease observations and yield results will be provided when they are available.

Ellendale trial

Table 4 Trial details, Ellendale trial
Property	Anthony Hollins, Ellendale
Crop/variety	Canola - Yr23
Treatments	Nil Fungicide application at 20-30% bloom (Prosaro® at 450ml/ha) Fungicide application at 40% bloom (Prosaro® at 450ml/ha) Fungicide application at 40% bloom (Aviator) Full control - spray (treatment) 2 + spray (treatment) 3
Replicates	Four

Ellendale results

A thorough disease assessment has been done in September, only minor levels of stem infection were observed at the site. Disease observations and yield results will be provided when they are available.

Acknowledgements

This trial is part of the GRDC funded project UM00051 National canola pathogen program including new molecular knowledge, pathogen evolution and control techniques.

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