Downy mildew found on purple velvet plants

Downy mildew, a disease known to damage dozens of plant species in Florida, has now been found on purple velvet plants in South Florida, UF/IFAS scientists say.

Purple velvet plants are popularly used for foliage and cut flowers, said Aaron Palmateer, associate professor in plant pathology at the UF/IFAS Tropical Research and Education Center in Homestead.

“The upside to reporting any disease, especially aggressive diseases like downy mildew, is to get the word out,” said Palmateer, who co-authored a paper on the finding that appears online in the journal Plant Disease. “This allows growers to take preventive action and to start applying fungicides labeled for downy mildew before a disease outbreak, which is the ideal approach for disease management. 

“The downside is the added expense of applying additional fungicides to control the downy mildew,” he said. “This is a disease that can kill the plant, so it’s a definite game-changer.”

Downy mildew pathogens are evolving and appear to be more prevalent in Florida’s ornamental plant industry. UF/IFAS scientists are working on ways to combat the impact of downy mildew on popular and economically important plants such as gardening impatiens and basil. In addition, several UF/IFAS plant pathologists and plant breeders are collaborating on research projects that may lead to the development of disease resistance, which is the most cost-effective approach for disease management.

Purple velvet, known scientifically as gynura aurantiaca, comes from Java and adapts well to South Florida landscapes, but it’s mostly used as a potted plants for home and business interiors.

Palmateer and his colleagues confirmed the downy mildew on purple velvet on about 30 percent of approximately 1,000 plants from a Homestead nursery.