A free light leaf spot testing service has opened for the 2021-22 oilseed rape growing season with a simplified process.
Leaf samples will be assessed by ADAS experts for signs of light leaf spot and other diseases, with the results helping growers to adapt their fungicide programmes.
Light leaf spot is an airborne polycyclic disease, capable of several infection cycles each season. Severity and incidence varies from year to year and is driven by weather conditions.
Temperatures between 4 and 20°C and wet conditions are ideal for infection and spread within the crop.
The disease can also be difficult to spot; tiny sugar-like spores can occur on either side of the leaf.
Rosalind Martin, combinable fungicide campaign manager for Bayer, which runs the initiative, said: “Fungicides perform best when applied in a protectant scenario against light leaf spot, so it’s important to get the timing right.
"If growers can get identify the disease in the early stages of infection, decisions can be made about fungicides in a timely way, to protect the crops yield potential through winter.”
The initiative is run in partnership with ADAS. Philip Walker, arable plant pathologist, explained that prevalence of light leaf spot in oilseed rape crops had been increasing since the initiative began.
Traditionally, light leaf spot was mainly thought to be a disease problem for crops in the North of England and Scotland, he said.
However, results from samples assessed since 2017 have shown positive signs of disease from all OSR growing regions, indicating that light leaf spot is now endemic across the UK.
“At the end of March 2021, light leaf spot was found in 59 out of 60 counties tested, covering most of the oilseed rape growing areas of England, Scotland and Wales," Mr Walker said.
"In addition, the number of samples that have tested positive has gradually increased year on year, despite the total number of samples received remaining roughly the same.
"In 2018 and 2019, 49% of samples tested were positive for light leaf spot, increasing to 68% in 2020, and 79% in 2021,” he added.
Oilseed rape growers and agronomists can request a sample pack direct from Bayer’s website.
