VIRUS ETIOLOGY OF FOLIAR VEIN-FLECKING OR RING PATTERN, AND FRUIT RUSSETING OR BLOTCH ON APPLE

Abstract

Virus isolates were obtained from trees of seven apple varieties, each affected with vein-flecking or ring patterns on the foliage, or ring-russeted, pitted or blotched fruits, or various combinations of these symptoms. When bud-inoculated to seven test varieties of apple, these isolates all differed from one another in the symptoms induced. This is interpreted as evidence that the isolates contained distinct viruses, virus strains or virus composites. All isolates affected varieties other than those in which they had occurred. Symptoms induced on the leaves of test varieties included vein flecking, minute ring patterns, coarse ring and line patterns, and vein-associated coarse blotching; those on the fruit included tenuous, single russet rings, tenuous or coarse ring russet networks, coarse, raised ring russeting, shallow pitting and dimpling. Two isolates induced bark or wood symptoms on test varieties.