Pink Rot Alert Given Idaho Growers

Published online: Jul 13, 2004
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Trying to prevent outbreaks of pink rot this month and next, an alert was given by the University of Idaho College of Life Sciences today.

Dr. Jeff Miller and other scientists are asking growers to scout their fields for signs of pink rot and send suspect plants to be evaluated.

Miller and postdoctoral fellow Lyndon Porter of the Aberdeen, ID, R and E Center are evaluating resistance to the fungicide mefanoxam in the pink rot fungus, Phytophthora erythroseptica.

Miller says tests conducted over the past three years indicate that more than 75 percent of this fungus' isolates from infected eastern Idaho tubers are already moderately resistant to mefanoxam, a chemical that's intended to control the disease.

Miller asks growers to start watching for premature wilting and roots with unusual brown-to-black lesions. Top priority spots to check are both waterlogged and water-stressed areas, high, dry ridges, saturated lowlands and rows beneath end guns. He says wilting could be a sign of another disease, like early dying, but he doesn't want growers to just assume that.

Pink rot infects tubers via fungus-infested soils. Although signs of wilt develop at the bases of stems, the worst damage occurs in the tubers themselves. When affected tubers are cut open, their boiled textured interiors turn pink, giving the disease its name. These discolored interiors are neither mushy nor slimy, but other diseases, including leak and bacterial soft rot, can quickly break down affected tubers in storage.

Growers with questions should call Miller or Porter at (208) 397-4181.