Effects of early winter gibberellic acid and mineral oil applications on flowering of young non-bearing clementine (Citrus reticulata Blanco.) and satsuma (Citrus unshiu Marc.) trees

Abstract

Gibberellic acid (GA₃) and heavy mineral oil (Bac-oil) treatments, either individually or in combination, applied during the flower initiation period in early winter (April to July) were evaluated as a means to reduce flowering levels in young non-bearing citrus trees over four seasons (five trials). GA₃ and mineral oil, either individually or in combination applied late in May to late June, markedly reduced flowering. Peak response tb-GA₃coincided with a significant reduction in bud sprouting. The winter application of GA₃, specifically, and possibly in combination with mineral oil to inhibit flowering, and enhance early vegetative growth on young trees may be utilised commercially. Results from these experiments suggest that optimum application time seems to be during late May to late July. However, this time is likely to vary somewhat from year to year depending on prevailing climatic conditions.