Diseases of Sunflower

Abstract

Sunflower (Helianthus annuus L.) has become a popular cut flower in the United States and globally. Easy to grow, bright and cheerful large flowers, with ray flowers from white to yellow to orange to magenta, it is often a centerpiece in mixed bouquets. Sunflower and the rest of the Helianthus genus are native to North America, and, as such, there is a native population of disease organisms and insect pests that can be a production challenge. Fortunately, ornamental sunflower and oilseed sunflower are the same species, and thus genetic advances made with oilseed germplasm can be readily transferred to ornamentals, if the need arises. The major diseases posing threats to ornamental sunflower are the same as those threatening oilseed sunflower hybrids, namely downy mildew, rust, Phomopsis stem canker, Sclerotinia wilt, Verticillium wilt, and charcoal rot. However, greenhouse production presents a different environment, and thus, there can be diseases affecting cut sunflowers that are seldom seen under field production. General management strategies for diseases of florists’ crops may be found in the introductory chapters on integrated disease management.