UF/IFAS researchers shared information on two products with a proven track record in the fight against citrus greening at a recent seminar.

A recent virtual seminar saw two UF/IFAS researchers sharing information on two products that have shown to be effective in the fight to combat citrus greening, also known as HLB. According to a Citrus Industry article, UF/IFAS horticulturists Tripti Vashisth and Fernando Alferez shared information on both gibberellic acid and brassinosteroids. See the details below.

Products That are Effective Against Citrus Greening

Takeaways concerning both products that are effective against citrus greening included:

Gibberellic Acid (GA)

  • A 2016–22 trial of GA-treated Valencia orange trees showed that the trees dropped less fruit and increased fruit yields compared to trees in the untreated control
  • The results extrapolated to “360 boxes per acre for the GA-treated trees compared to 285 boxes per acre for the control.”
  • An economic analysis proved GA treatments to be worthwhile, with treated trees offering a “yearly average “profit differential” ranging from $452 per acre to $1,712 per acre when compared to untreated trees.”
  • “In another trial, the use of GA plus 2,4-D reduced preharvest fruit drop by 18%…Fruit size also improved in the GA plus 2,4-D trial.”
  • “Applying too close to bloom could negatively affect bloom/fruit set,” Vashisth shared. “Do not apply after Jan. 10, possibly Dec. 31 … If early flowering is predicted, stop sooner than January.”


  • “The use of brassinosteroids” on newly planted citrus trees “reduced the rate of HLB infection after six months to only 25%,” while the rate without brassinosteroids is currently 100%.

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