Florida citrus growers should keep an eye out for these fungal foliar diseases this year.

Citrus greening is the greatest concern for Florida citrus growers, but there are also fungal foliar diseases to watch out for as well. These diseases can “can nibble away at productivity by reducing overall tree health” according to an article by associate professor, Megan Dewdney, with the University of Florida Institute of Food and Agricultural Sciences Citrus Research and Education Center in Lake Alfred, and published as a Citrus Industry article. Some, like postbloom fruit drop, can have a serious impact on harvest numbers. See a summary of each fungal foliar disease to watch for, below.

Citrus Fungal Foliar Diseases

Greasy Spot: the fungus Mycosphaerella citri causes both greasy spot and rind blotch, according to the article. The spores originate from the leaf litter beneath the trees. If either issue was a problem last year, or If leaf drop was high over the winter, the article advises to increase control efforts, such as to “increase the number of gallons per acre to 250 and slow the tractor speed for more thorough wetting of the canopy and/or apply a third spray in August.”

Melanose: Caused by the fungus Diaporthe citri, Melanose reproduces in dead twigs. Both hedging and copper are control options.

Black Spot: increased by wet weather, fungicides like “the strobilurin fungicides, Enable, copper, and the pre-mixes Amistar Top and Pristine” or those used for canker should be used.

Postbloom Fruit Drop: According to the article, “There is an 80 percent chance to have another El Niño winter. This means that the risk of PFD is elevated compared to 2017 and 2018,” and advises growers “to scout their flowers for the reddish, brown discoloration that is indicative of infection.” Fungicide applications containing a strobilurin are the leading control option, with the article recommending the use of the PFD forecasting tool released in January 2018.

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