Optimizing Gibberellic Acid Applications in Florida Citrus

Josh McGillFruit Drop, HLB Management

Tripti Vashisth, University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) associate professor of horticultural sciences, has dedicated several years of research into the use of plant growth regulators like gibberellic acid (GA) to fight fruit drop in citrus.

Gibberellic Acid

In the August All In For Citrus Podcast, Michael Rogers, director of the UF/IFAS Citrus Research and Education Center, interviewed Vashisth on her research to explore how growers can get the most out of GA applications in citrus.

In addition to the number of applications and timing, Rogers and Vashisth discussed other factors impacting GA efficacy. Rogers emphasized the importance of citrus nutrition as the foundation of production programs. He said PGRs can be used to build on this foundation and help fruit retention. Vashisth agreed GA has an additive effect when applied correctly.

“We have seen that five applications of GA from September to January in Valencia have helped in improving the yield over time by reducing fruit drop, improving vegetative growth and overall building a healthier tree through better plant defenses,” she said. “GA is helping in multiple ways.”

Vashisth provided details on how each of the applications specifically benefit trees during the growth periods of citrus between September and January. If economics force growers to apply less than five applications, trees will not get the full benefit provided by sequential applications during these important growth stages.

In addition to GA, Rogers and Vashisth discussed new and ongoing research with the use of 2,4-D to improve fruit retention in HLB-affected orange trees.

Growers interested in fighting fruit drop with plant growth regulators will not want to miss this episode of All In For Citrus. The podcast is a joint project of UF/IFAS and AgNet Media. Listen to the podcast here.

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Frank Giles


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