US: Researchers warn of potential for volunteer, late blight challenges in Idaho

Soil temperatures in most of Idaho potato country never got low enough to kill volunteer spuds, which could provide a host to carry the late blight pathogen into this season, University of Idaho Extension researchers warn. UI Extension potato pathologist Phillip Wharton developed a predictive model to weigh the risk of volunteers, assessing average temperatures in the top 6 inches of soil from November through March. During the winter of 2015-2016, average monthly soil temperatures remained above 31 degrees in all nine growing areas he tracked, except for Parma, which had an average soil temperature of 28 degrees for January. As a result, growers should expect a repeat of last season’s volunteer spud problems, said Kasia Kinzer, a UI Extension potato seed specialist who with Wharton recently co-authored a report on the volunteer outlook. More