Yorks patches puzzle
STUNTED patches of wheat are showing up in Yorkshire, prompting debate about their cause.
Fieldcare technical co-ordinator Alison Clayton believes the take-all type symptoms could be linked to the fungus which gives rise to black scurf and stem canker in potatoes. In places 60-70% of fields are affected, says Miss Clayton. "The ears are very thin."
Laboratory tests by CSL confirm the presence of Rhizoctonia solani on the roots of plants sent in by the Thirsk-based firm.
Rarely seen in wheat, the fungus is related to Rhizoctonia cerealis which causes sharp eyespot. But the samples examined showed no symptoms of that disease, says the CSLs Charles Lane.
R solani, which also causes damping off in seedlings, can survive in the soil on dead plant matter, he adds. "The problem is it could be building up vast amounts of inoculum for future years."
ADAS pathologist Bill Clark believes the Yorks patches are more likely the result of sharp eyespot. Many varied fungi, including R solani, inhabit soils, he notes. "That doesnt mean it has caused the problem." *