Nottingham university warns of ‘forgotten disease’ in cereals

The University of Nottingham is warning tillage farmers of a “forgotten disease that still lurks in more than half of English wheat fields”.

Dr. Rumiana Ray, an agricultural researcher at the university, highlighted that the fungus rhizoctonia cerealis – which can cause yield losses of up to 30%, could be “lying unnoticed” in 54% of wheat fields in England.

Dr. Ray, an associate professor of plant pathology, explained that the fungus is traditionally associated with stem base disease; sharp eyespot; causing lodging; and empty white ears.

Research at the University of Nottingham has apparently also shown that rhizoctonia can cause damping-off much earlier in the season, in which germinating seeds rot away in the soil – resulting in reductions in crop emergence and plant numbers.

“Rhizoctonia is a soil-borne risk. It is well known that other important seedling diseases associated with microdochium and fusarium species cause damping-off and reductions in plant stand, but we didn’t know rhizoctonia cerealis can do the same,” said Dr. Ray.

A study by the university of over 100 wheat fields in England found that 54% of them contained rhizoctonia cerealis in the soil. The most effected area was the Midlands, where 65% of the fields studied were infected with the fungus.

“Ultimately, rhizoctonia can cause yield losses in cereals of up to 30%. However, farmers rarely, if ever, target the disease for specific treatment. Instead, control usually relies on any cultural methods that the farm may be using at the time,” Dr. Ray continued.

Of these, it is unlikely that drilling date has much effect on rhizoctonia cerealis, although diversity of crop rotation and cultivations will have some effect.

In terms of seed treatment, further research by the university seems to indicate that treatment with the fungicide sedaxane boosts wheat emergence by 23%, compared with untreated seeds, in a field that was inoculated with the fungus.

The treatment also increased root length by 50% – almost up to the same length for an uninfected plant.

“The seed treatment proved very effective at protecting seedling growth and increasing establishment through reductions of disease caused by all three pathogens – rhizoctonia cerealis, microdochium and fusarium. The greatest yield increases were seen against rhizoctonia cerealis and microdochium nivale.” Dr. Ray highlighted.

She concluded: “A big question has been which is the worst pathogen at the seedling stage – fusarium, microdochium or rhizoctonia? From inoculated trials it appears it is both rhizoctonia cerealis and microdochium nivale. Rhizoctonia cerealis has been forgotten, but it should not be overlooked.”