Staying alert to signs of sclerotinia infection will be key to maintaining OSR yield and quality, as current weather conditions are conducive to the disease.
“Sclerotinia can cause losses of up to 50% per affected OSR plant, so minimising the infection risk and potential damage during this crucial period is important,” says Geoffrey Bastard, Certis’ technical specialist.
“The level of rainfall and high soil moisture this spring has led to favourable conditions for development of the disease, and the rise in temperature over the next few weeks will increase risk,” he says.
“The highest risk period is when temperatures are above seven degrees with a relative humidity of less than 80 percent. The crops at most risk will be those which have been affected by the cold winter, or have existing damage from pests such as pigeons.”
Geoffrey explains that monitoring these high-risk crops will be key, especially as sites in the west, south and east of the country have already experienced high-risk conditions for the disease.
“I would suggest signing up to the AHDB sclerotia risk alerts which are published regularly throughout the flowering period and offer an insight into local disease risk.”
He adds that when it comes to controlling the disease, the choice between a one, or two-spray approach will come down to both local disease pressure and length of flowering.
“Control programmes will vary according to region, farm and crop, so it’s important to monitor plant development and assess the risk on a bespoke basis.
“Where local risk is high, an application early in the flowering period will be appropriate. However, this may mean that a second spray, 10 to 14 days after the initial spray, is required to protect the crop until the end of the risk period, after flowering has stopped,” he says.
“If a two-spray programme is required this spring, the inclusion of Topsin or Taurus (thiophanate-methyl) can be a cost-effective solution to protect yield, while offering a different mode of action for resistance control.
“OSR is one of the most profitable crops for many growers, so acting quickly, when conditions require, will help to protect your investment,” he says.
Sign up to the AHDB sclerotinia risk alerts on their website: www.cereals.ahdb.org.uk