Researcher makes first finding of disease strain in Idaho spuds

A researcher has confirmed the Idaho potato industry’s first known infection of a strain of the fungal pathogen Rhizoctonia solani that thrives in rotations with crops in the brassica family. University of Idaho plant pathologist James Woodhall found the infected tuber while digging spud samples in Ada County, scouting for a bacterial disease affecting potatoes called zebra chip. Woodhall said the potato showed symptoms of Rhizoctonia, but he was surprised when it tested positive for the AG2-1 strain, which he researched while working in England. Though AG2-1 had never previously been identified in an Idaho potato field, Woodhall suspects it’s been present in the state for a long time but had gone unnoticed. It’s also present on potatoes in other states. Woodhall acknowledged AG3 — the strain that causes more than 70 percent of Idaho’s Rhizoctonia infections — is far more aggressive than AG2-1 in potatoes. More