You are here

Share page with AddThis

Go for green with OSR leaf

Agronomy Issues
08.04.2019
OSR flower petal stuck on petiole and resulting sclerotinia infection
Sclerotinia protection and green leaf retention could prove even more important on variable crops recovering from CSFB larvae damage this season

Sclerotinia can have a devastating hit on oilseed rape yields in a high pressure situation. It is more than a decade since the last serious national outbreak, but there are still reported incidences every year.

Where growers have a history of sclerotinia incidence on the farm, particularly when the season conspires to create disease pressure - typically with warm, wet weather through the flowering period - Syngenta’s Georgina Wood suggests growers will benefit from additional benefits of green leaf retention with Amistar, alongside its disease control. 

Open OSR canopy to let in light

“This season the greening effect could be particularly important to help crops recover from the impacts of cabbage stem flea beetle larvae damage,” she advised iOSR growers. “In many instances crops have shed large numbers of leaves where the petioles have been damaged.

“They will now be reliant on compensatory new growth, to capture sunlight and fill seeds with oil.”

Furthermore, Georgina warned that the larvae damage has created widespread variability between plants, which is anticipated to lead to an extended flowering period.

NIAB has already warned growers of the protracted flowering period, which it reports may need a two or even three spray disease control strategy.

With a target 6000 to 8000 pods per m2, Georgina pointed out that OSR seed yield is determined by the amount of photosynthesis carried out by the crop during a 19 - 25 day period after mid-flowering, with green leaf the primary source of energy for seed fill. 

Georgina Wood

 ADAS trials have shown that a single Amistar application can maintain an additional 0.5 GAI 10 days after end of flowering and still 0.25 greater GAI 20 days later.

“Timing of fungicide applications is going to be important this season,” she suggested. “If sclerotinia risk rises, then the conventional early to mid-flowering prevention will be crucial." 

"But growers will also still likely gain from later applications, targeted at healthy green leaf retention and preventing leaf spot infections.”

In both instances, she believes the greening effect of Amistar will boost the essential oil content of seed and overall returns for growers.  

Sclerotinia key risk factors:

Wet and warm conditions

OSR crops in flower

Length of rotation, including other host crops

Presence Sclerotinia spores

Fungicide programme applied

Relative humidity >80% + Air temperature >7°C + >23 hours duration = Greatest risk of sclerotinia infection

Find out more news on the dedicated iOSR pages - click on the links to view:

CSFB focus - iOSR Focus Site and growers experience of crop removal to take away larvae

Easy way to count CSFB larvae infestation

iOSR Focus Site results of mixed crop sowing

iOSR logo