Overview
The UF/IFAS citrus faculty at the research and education centers recommends quick attention after a hurricane to prevent further damage to vulnerable root systems and future fruit drop.
Flood waters resulting from heavy rains can severely impact roots already diminished because of HLB (Huanglongbing; citrus greening). Phytophthora is a pathogen that attacks citrus tree roots, which are already weakened by HLB. Wet conditions, especially flooded groves, increase the possibility of phytophthora infection in groves with historical problems. If standing water has occurred in groves with phytophthora problems, growers should evaluate for root damage and treat accordingly.
Past hurricanes have caused damage that resulted in fruit drop, and the fruit left on the tree is more vulnerable to accelerated drop in the coming weeks due to canopy damage. UF/IFAS recommends applying gibberellic acid in the weeks following the hurricane to support the tree’s ability to hold on to its fruit.
Extensive leaf loss is going to stress already stressed trees. It is quite likely that extensive leaf loss with good soil moisture will induce new growth. A GA application after a hurricane can help rehabilitate trees and improve leaf growth.
Some growers are already using GA in a series of applications to improve fruit production and should continue to do so. Growers not using GA in this way are encouraged to make at least one application to encourage leaf growth lost to the hurricane, which will support future fruit production.
Tree defoliation also poses the risk of Asian citrus psyllids being attracted to any new flush that the trees will produce. It would be wise to watch for pest flare-ups associated with intense flushing.
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