For decades, Florida growers have found copper-based products to be an effective means of controlling a plethora of citrus-related diseases.
But the use of copper-based products has exploded since 1995, when growers turned to the metallic element to fight the modern menace of citrus canker.
Now, producers are growing increasingly anxious about the effect copper buildup may have on their groves. And they’re increasingly afraid that the day may come when pathogens display copper resistance.
That’s why plant pathologists like Pam Roberts and Jim Graham are working to uncover alternatives to the popular go-to product whose days may be numbered.
Roberts, professor of plant pathology with the University of Florida Institute of Food and Agricultural Sciences’ Southwest Florida Research and Education Center at Immokalee, is taking a program approach to fighting canker that combines copper with other disease-fighting tools.
So far, she hasn’t found anything more effective than copper to control bacterial diseases, such as citrus canker. But there are products that she says work just as well.
Some of the tools that look promising include Serenade Max, manufactured by Davis, Calif.-based AgraQuest Inc.; Regalia from Marrone Bio Innovations Inc. of Davis; and Actinovate SP from Natural Industries Inc. of Houston. All currently are registered for use on Florida citrus.
She also has tested Actigard 50WG from Syngenta Crop Protection LLC of Greensboro, N.C., which is not yet registered for use on Florida citrus.
“There isn’t anything that I would say to spray instead of copper,” she says. “But I see potential in using some of these products.”
This has not been a good year for Roberts’ trials because of unusually high citrus canker pressure in many parts of the state that no product or combination of products can manage.
“It’s just been out of control,” she says.
Roberts says she’s hopeful that the outbreak this season is the result of a heavy rainstorm in March before growers had a chance to spray for canker and is not an indication of things to come.
“Everyone is pretty dismayed by the severity of canker this year,” she says.