Biennial bearing of citrus is a major problem that must be resolved in the near future. This problem mainly arises due to declining tree vigor and excessive flowering. In satsuma mandarin (Citrus unshiu Marc.) , it was observed that application of 2.5 ppm gibberellic acid (GA) along with machine oil emulsion during the winters can suppress flowering in the following year. The same effect is observed when the adjuvant is mixed with 2.5 ppm GA and is applied partially to the citrus trees.

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... there are no adverse effects if urea is applied to restore the tree vigor. However, for "Shiranuhi citrus cultivar," spraying 2.5 ppm GA mixed with machine oil emulsion or adjuvant was found to be much more effective than GAmixed with urea. Therefore, plant growth regulators, such as GA, can be used at a lower concentration with penetrant adjuvant, to have the same effect as observed with the prevailing concentration. Reduction in excess flowering can potentially prevent biennial bearing. Moreover, using an adjuvant can lower plant growth regulator concentration and the cost.