Although citrus black spot has only been detected in commercial groves in five Southwest Florida counties, it is still spreading and likely to be in additional counties, according to plant pathologist Megan Dewdney. The five counties with detections are Charlotte, Collier, Glades, Hendry and Lee. Dewdney is a University of Florida Institute of Food and Agricultural Sciences associate professor at the Citrus Research and Education Center in Lake Alfred.
In a virtual Citrus Expo presentation, Dewdney said Hurricane Irma in September 2017 probably moved black spot to new areas in Central Florida. “Irma went straight up (north) through black spot regions,” she said.
According to Dewdney, those who are downwind of black spot-infected groves are at significant risk for the disease and should learn to recognize its symptoms and scout for it. She recommended waiting for fruit color break or about a month before harvest to scout. Scouters should visit multiple locations in groves, especially along roads or near staging areas for equipment or fruit trucks. Dewdney said declining trees tend to have more disease, and that sunny sides of trees tend to express disease symptoms first.
Citrus black spot can cause up to 60 percent yield loss and some fruit drop in severe situations where there is little management of the disease, Dewdney reported. But fruit drop levels of 10 to 20 percent are more common in a minimally managed grove, she said. She noted that 10 to 20 percent is “still a significant number of fruit.”
Dewdney also discussed symptoms, the disease cycle, management options, research and more. See her full presentation here. All Citrus Expo presentations and the CEUs that can be earned by watching them will remain available through the end of 2020.
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