by Brad Buck, University of Florida/IFAS
Florida’s winters are usually dry, but the wet winter of 2015-2016 helped spread pathogens that destroyed ornamental plants in Miami-Dade County. That’s a problem in an area where the industry generated an estimated $998 million annually in sales in 2015, University of Florida Institute of Food and Agricultural Sciences researchers say.
Damage figures are not yet available from the 2015-2016 winter rains, but UF/IFAS scientists have found the pathogens Phytophthora and Pythium caused the most destruction. Rain spreads those pathogens, said Georgina Sanahuja, a post-doctoral researcher at the UF/IFAS Tropical Research and Education Center in Homestead, Florida.
Meteorologists consider Florida’s “dry season” to run from Oct. 1 to March 1 and the rest of the year to be the “wet season.” But last year, the “dry season” wasn’t so dry, because of El Niño, which brought more rain than South Florida has seen since records were kept starting in 1932, a new study published in the journal HortTechnology says.
When last winter’s rains hit, nursery growers brought their plants to the UF/IFAS Extension Plant Diagnostic Clinic in Homestead. Plants suffered from root rots, crown rots and blight diseases, Sanahuja said.
“The ornamental industry has exceedingly high standards for plant quality, and there is often zero tolerance for disease symptoms caused by plant pathogens,” Sanahuja said.
In the study, Georgina Sanahuja, a post-doctoral research associate in associate professor Aaron Palmateer’s ornamental plant pathology program at the Tropical REC, in collaboration with Vanessa Campoverde, a commercial agriculture and ornamentals agent with UF/IFAS Extension Miami-Dade County — documented four years of environmental conditions in South Florida that caused the plants to get diseases. They studied Oct. 1 to March 1 of 2015-2016 and compared it the same period from the three previous years.
Florida’s ornamental plant industry flourishes because the weather allows for year-round growing, Sanahuja said. A UF/IFAS economic report from 2015 estimates the economic output contribution of the environmental horticulture industry statewide at $21.08 billion annually.
UF/IFAS experts suggest nursery owners and managers routinely scout for root rot, crown rot and blight diseases. Diseases caused by Pythium and Phytophthora spread quickly and require chemical applications when the weather forecast calls for heavy rains, Sanahuja said. UF/IFAS experts also recommend removing and discarding severely affected plants, and using proper fertilization and irrigation for better plant health.