If citrus greening wasn’t enough, citrus growers now have another disease to worry about

In Growing Produce

by Frank Giles

The notion that anything would knock HLB out of the headlines in the Florida citrus industry is hard to believe, but postbloom fruit drop (PFD) has grabbed the attention of growers across the state. For the past three seasons, the ailment has come back and is epidemic in some groves.

While HLB clearly enhances PFD, the problem, caused by the fungus Colletotrichum acutatum, has been around for a long time, being first formally described in Belize in 1979. The fungus will infect flowers of all species of citrus, creating orange-brown lesions in the blooms. The fruitlets will then drop leaving buttons behind. In more normal years, PFD effects Navel and Valencia, however this past season, Hamlins also were impacted.

According to the 2016 Florida Citrus Pest Management Guide, most spores of the fungus are produced directly on the surface of infected petals.

Spores are dispersed by rain to healthy flowers where they infect within 24 hours and produce symptoms in four to five days. The fungus survives between bloom periods as resistant structures on the surface of leaves, buttons, and twigs. Flowers are susceptible from the pin-head stage (with white tissue present) until they are open.

HLB’s involvement comes with erratic bloom it has triggered in citrus trees, which makes it more difficult for growers to time fungicide applications for maximum efficiency.

Read the rest of the story in Growing Produce.

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