Use of IKI leafroll test to reduce net necrosis storage losses of potatoes

Abstract

An iodine-potassium-iodide (IKI) starch staining procedure was adapted for use on potato plant leaflets to estimate the frequency of potato leafroll virus (PLRV) infection in potato fields prior to harvest. Large increases in the percentage of tubers with net necrosis occurred during storage among tubers from fields with high PLRV infection rates. Such fields were reliably identified prior to harvest by the IKI test, so their tubers could be processed at harvest to avoid net necrosis storage losses. The test could be performed on hundreds of samples per hour by untrained personnel with commonly available equipment. PLRV infection frequency varied widely in Columbia Basin potato fields. Most infected plants expressed no symptoms but could be detected by the IKI test before harvest. High rates of virus dissemination apparently occur late in the growing season in the Columbia Basin