Citrus Canker Management Through the Year

Ernie NeffDiseases

citrus canker
Canker lesions on citrus leaf

Plant pathologist Megan Dewdney with the University of Florida Institute of Food and Agricultural Sciences offers suggestions for managing citrus canker at different times of the year. She is an associate professor at the Citrus Research and Education Center (CREC) in Lake Alfred.

citrus canker
Megan Dewdney

Dewdney suggests that copper sprays begin when fruit reach three-eighths of an inch in diameter in groves with a history of canker incidence. “These days we can’t really … rely on the calendar,” she says. “We need to see what our average fruit size is and see when the majority of our fruit hit that three-eighths critical time when the fruit becomes particularly susceptible. Otherwise you end up potentially missing that critical window and getting a large quantity of fruit infection that you just can’t get ahead of.”

For those not using a copper model to time sprays, Dewdney offers some advice: “I would definitely recommend sticking to a 21-day (spray) schedule” in an effort to keep fruit covered with copper. She likes that schedule because fruit can outgrow its copper coverage, “particularly at this early season, the fruit really expands so quickly that it is hard to keep them covered … That (21-day schedule) on average works out the best.”

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Using an air-blast sprayer behind a slow-moving tractor instead of aerial application for copper sprays is best, Dewdney says, because “coverage is king.”

She also offers timing recommendations for curtailing copper sprays. “If you’re growing processed fruit, unless you’ve got a really raging problem, probably ease up on the canker management once those fruit hit that 1.5-inch in diameter,” she suggests.

Dewdney gave her canker recommendations as part of a March 3 OJ break hosted at the CREC by citrus Extension agent Chris Oswalt. Approximately 30 growers and others attended the meeting.

Hear more from Dewdney:

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About the Author
Ernie Neff

Ernie Neff

Senior Correspondent at Large