Rapid test for light leaf spot is now available

• Early warning of damaging disease

• Results identify best application slot

• Helps growers save time and money

A simple, rapid test to identify the most economically damaging disease in the UK for oilseed rape will be available to buy from September.

Light leaf spot can cause losses in yield of up to 30% in rape – equivalent to £80 million in lost returns, says Microgenetics. The company has now created what it claims is the fastest and most accurate test for the disease.

Called SwiftDetect, the test will be available from 12 September with a one business-day turnaround, says the company’s Chris Steele. Testing will help identify the best time to apply fungicide, he adds.

Once signs of light leaf spot are visible, sprays don’t work as well, says Mr Steele. “SwiftDetect will provide farmers with the means to identify the golden window of opportunity when fungicides are at their most effective.

“It will optimise fungicide efficacy, delay costly fungicide applications in low detection fields and target applications to specific fields with high and early pathogen detection. This can potentially reduce overall cost and minimise crop protection use.”

Andrew Hartley, arable technical manager for seed breeders DSV, says using SwiftDetect to identify when disease is not present is as valuable as when it is. “The hardest decision in agriculture is always not to do something,” says Mr Hartley.

“Many farmers, myself included, have been guilty of spraying crops on a predetermined particular calendar date, with sometimes little knowledge of whether or not disease is in the plant.

“If you have information that definitely tells you there’s no disease, then the likelihood is you wouldn’t spray for that disease, which would save you time and money, and would be better for the environment.”

Mr Hartley adds: “I think farmers will have to justify why they’ve sprayed something in the future and what they’ve sprayed for. One day, it’s very likely that conducting these tests will become part of general farming practice.”

Disease forecast

Rainfall is currently used by many as a way of predicting the likelihood of light leaf spot occurring. But trials in Scotland and England suggest that this isn’t always a reliable means of forecasting, says Mr Steele.

“The trials revealed a positive link between rainfall and light leaf spot detection. But none was found in one variety, Dart, despite high levels of rain. Favourable environmental conditions do not guarantee disease presence.

“SwiftDetect could help farmers and agronomists select varieties more accurately. Despite the resistance score of Crossfit and Duplo both being 5, a significant difference in pathogen load was evident between the two.”

Mr Steele says this suggests SwiftDetect could be used to assess variety resistance more accurately, helping growers make informed and up-to-date decisions. The test is being adapted for other diseases, including phoma.