Abstract
The susceptibility of 29 cultivars of chrysanthemum, representing various types of growth, to crown gall was studied. Two isolates of Agrobacterium tumefaciens: chrysanthemum and apple were used for testing plants. The inoculation was made to the stem base of rooted cuttings and places of pinching off. The first method gave larger galls on most tested plants and only three cultivars were resistant to inoculation with both A. tumefaciens isolates. Weak symptoms were obtained after cutting of stem tips, thus plants of 9 and 5 cultivars (in subsequent tests) showed no symptoms. Only three chrysanthemum cultivars were resistant to crown gall in all tests: Epidote Jaune, Epidote Orange and Epidote Rouge, all belonging to potted chrysanthemum. Plants of Maracas cultivar were resistant when bacteria were applied to the wound of stem tips. In all tests, the apple isolate was weak pathogenic, thus no gall were observed on many cultivars.
Keywords
chrysanthemum; crown gall; susceptibility