Diseases of Chrysanthemum

Abstract

Chrysanthemums originated in China, but its major phenotypic selection occurred in Japan. The plant is sold as a cut flower, as a potted flowering plant, or as a garden plant. By manipulating day length, the plant can be produced year-round. Intensive production during the first half of the twentieth century resulted in devastating diseases, such as those caused by the fungi Ascochyta, Septoria, and Verticillium, which severely threatened the chrysanthemum industry, but are no longer problems because of the widespread use of fungicides and the clean stock programs employed by the key producers. However, several new major diseases of chrysanthemums have emerged that limit production and affect quality including bacterial infections, root rots, rusts, and viral and viroid infections.