Seed treatments, variety selection, and fungicide programme are key areas of research in the battle against rhynchosporium, said Simon Oxley, senior pathologist for SAC.
Rhynchosporium can be found on seed and even certified products can be infected. None of the existing seed treatments are effective, so SAC is researching the effect of hot water seed treatments, said Dr Oxley.
Early disease levels had been reduced where hot water treatment was used, but later in the season disease levels increased. Because seed needed to be heated to high temperatures it could be damaged by the process and in one case germination had been significantly reduced. “More research is needed to see if it has a real benefit to the grower,” he said.
Variety choice was also important and anything with a rating of three, four or five could suffer badly in Scottish conditions. Growers should consider planting varieties with higher ratings, but be aware that these could also become infected.
For example, some populations of rhynchosporium, particularly those in the Lanarkshire area could badly infect Retriever, he said.
Early spring – around GS30 – was the most cost effective time to control rhynchosporium infections with fungicide inputs, but growers should save the strongest products for stem extension. “If you’ve got rhynchosporium, it has to have a prothioconazole base in it somewhere to get the effect of eradication,” he said.