Gibberellic Acid for HLB-Affected Trees

Ernie NeffHLB Management

Tripti Vashisth

Horticulturist Tripti Vashisth discussed the use of gibberellic acid (GA) in HLB-affected trees at a recent, well-attended OJ Break in Bartow hosted by multi-county citrus Extension agent Chris Oswalt. Vashisth is an assistant professor at the University of Florida Institute of Food and Agricultural Sciences Citrus Research and Education Center.

Vashisth told growers that HLB-affected trees are under continuous stress and have off-season and prolonged flowering, making grove management difficult. She hopes that using GA to reduce flowering might be helpful.

Not many growers are using GA right now, largely because there hasn’t been much information about how it works on HLB-affected trees, Vashisth said. “However, I’ve been getting a lot of interest in GA from the growers right now.”

In research on GA, “We did see improved fruit size (and) improved fruit retention, which means possibly less drop, and better yield with GA” she said. She also believes GA may help maintain tree health.

Vashisth discussed the use of GA to help with postbloom fruit drop (PFD), a disease that has plagued many Florida growers in some recent rainy bloom seasons. She said fungicides can effectively control PFD, but that the long bloom periods common with HLB mean growers have to focus on keeping fungicides applied for a long time. “So the idea was that if we can use GA to make flowering more compact,” fungicides can be used for a shorter duration.

“It (GA use) is very encouraging,” Vashisth concluded. “I think GA does hold a promise, but I would like to bring some caution to the growers that if you are deciding to apply GA you have to find the right time to apply.” She suggested that growers try GA on a small block “until you become more familiar with it, and then go on a larger scale.”

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About the Author

Ernie Neff

Senior Correspondent at Large