KODA [9-hydroxy-10-oxo-12(2), 15(Z)-octadecadienoic acid] has previously been isolated from Lemna paucicostata, and is a compound known to promote flowering in plants. In this study, the effect of KODA on flower production and spring shoot occurrence in mature satsuma mandarin (Citrus unshiu Marc.) trees was examined in the field. The application of KODA in the summer or autumn had no discernible effect on flower production in the following year. However, when applied in summer, it promoted spring shoot occurrence in the following year, regardless of the number of flowers produced. In addition, C-KODA, a KODA analog, was more effective at producing this effect than KODA. The results suggest that the application of KODA or C-KODA may regulate spring shoot occurrence to improve the imbalance between the number of flower-bearing and vegetative shoots that leads to alternate bearing in satsuma mandarin trees.