Idaho's erratic weather conditions over the past two weeks, cool and slightly damp, coupled with irregular irrigations which have resulted from growers trying to keep water applications ahead of hot, dry weather, have probably led to the discovery of late blight in eastern Idaho this week.
University of Idaho potato specialists confirmed the find Tuesday, saying only that it was found in Bingham County, the state's largest-producing county with about 55, 000 acres. Late blight reports were made a few weeks ago in western Idaho.
This most dreaded of potato diseases has had the University's phones constantly ringing as growers try to find the best and most economical way to handle the problem.
The late blight spores can be carried in air currents downwind for up to 50-60 miles, which means if it found down the Snake River Valley it will most probably move up the valley. The normal flow of air currents is up the Valley, all the way to the Rexburg area.
Most growers now apply a preventative fungicide application early in the season, crossing their fingers they won't have to make other applications. Now, curative treatments will be needed if they intend to continue to grow their crop. If not, growers are advised to kill their vines to not only handle the problem in infected fields, but as insurance for neighboring fields.
Growers have been told that even if their vines are killed, dying, or in the process of being killed, a fungicide application could be necessary--even to applying one on the bare soil before harvest--to make sure the spores are not carried into storage where soft rot can develop.
But Dr. Phil Nolte of the University of Idaho says there is no information indicating the post-harvest applications are effective in stopping tuber blight.
"I'm not sure we're getting through to them just how much of a danger this late-season infestation is. If we get through without very many more rain events, we may be all right [in eastern Idaho]," he stated.