DWARFING AND CANOPY MANIPULATION TECHNOLOGY OF PERSIMMON IN KOREA

Maintaining low height has been a key practice for efficient management of persimmon orchards in Korea. Since no dwarfing rootstocks are commercially available to date, tree height is lowered most easily by heavy pruning, after which excessive shoot growth with low yield can hardly be avoidable. Therefore, the importance of stabilizing the vigor of lowered trees cannot be overemphasized. To lower tree height, large scaffolds are removed stepwise extending over several years. Leaving many one-year-old shoots at dormant pruning, thereby increasing leaf area as well as the number of fruits, significantly decreases the occurrence of water sprouts in vigorous trees with no appreciable yield reduction. Trunk girdling in early summer is one of the options to quickly reduce excessive shoot growth. When the shoots grow vigorously, the extent of fruit growth may be less than anticipated at the conventional level of flower bud thinning, which leaves a bud a shoot. Under such circumstances, it is recommended to leave 1.5 to 2 buds per shoot before flowering, followed by the final adjustment of fruit numbers after the physiological drop. When the lowered trees are vigorous, it is necessary to reduce N applications. Foliar application of prohexadione-Ca at 100-200 mg∙L^-1 (ppm) significantly reduces the growth of water sprouts and secondary shoots without adverse effect on the fruits. Combination of different measures may have to be considered depending on the degree of tree vigor.