Downy mildew confirmed on popular purple velvet plants

GAINESVILLE, Fla. -- Downy mildew, a disease known to damage dozens of plant species in Florida, has now been found on purple velvet plants in the southern part of the state, University of Florida/Institute of Food and Agricultural Sciences scientists say.

Purple Velvet aka Purple Passion, which now has been found

to have been damaged in Florida by the downy mildew pathogen.

Photo by Dr. Jianjun Chen, UF/IFAS. 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.