Laboratory assessments of the susceptibility of potato-tuber tissue to blight (Phytophthora infestans)

Abstract

Fifty five potato varieties were compared withMajestic for the resistance of their tuber tissues to infection byPhytophthora infestans (Mont.) de Bary in three kinds of test using 1. halved tubers; 2. tuber slices and 3. whole tubers. Tissue resistance was better indicated by the extent surface mycelium developed after the fungus had grown through a slice of standard thickness (Test 2) than by the density of surface mycelium on the inoculated surface (Test 1) or by the area of necrotic tissue (Test 1 and 3). Most varieties that suffer few tuber infections when grown as field crops were rated as resistant by these tests. Tissue resistance as assessed by these simple laboratory tests, which require only few replicates, could be used to select tuber-resistant varieties.