The UF/IFAS Tip of the Week maintains it’s time for Florida citrus growers to start scouting for postbloom fruit drop.

The UF/IFAS Tip of the Week, written by UF/IFAS associate professor Megan Dewdney, maintains that it’s time for Florida citrus growers to start scouting for postbloom fruit drop (PFD). In the accompanying Citrus Industry article, Dewdney shared information about PFD and what to look for to identify the disease. Explore the details below.

Scouting for Postbloom Fruit Drop

According to the article, PFD is a “flower disease mainly caused by the fungus Colletotrichum acutatum” which needs particular weather conditions to be able to infect citrus flowers. Temperatures between 72 and 79 degrees, and periods of leaf wetness of more than 16 hours—usually from rain—create the ideal conditions for the fungus. Longer periods of leaf wetness amid cooler or warmer temperatures can also lead to infection.

Tips for scouting postbloom fruit drop from the article include:

  • “If symptoms are present, the Citrus Advisory System will identify periods of increased PFD risk in your area when the main bloom comes.”
  • “Popcorn and opened flowers are the most susceptible to the disease, so concentrate scouting for symptoms on these stages.”
  • “PFD lesions are peach to pinkish brown on flower petals. Whole flower clusters show symptoms when conditions are perfect for PFD.”
  • “Fruitlets that develop from PFD-affected flowers turn chlorotic and fall off trees. Fallen fruitlets leave behind persistent calyces, also known as PFD buttons.”
  • “PFD buttons can be differentiated from calyces caused by natural fruit fall when removing them from trees. While calyces that originated from natural fruit fall are easily removed, PFD buttons are not easily taken off trees.”

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