Hormone-induced Parthenocarpy in the Calimyrna Fig and a Comparison of Parthenocarpic and Caprified Syconia.

The problems associated with caprification (pollination) of Calimyrna figs and the desirability of standardizing or, still better, eliminating this cultural operation have been discussed (5). Because of its relatively low cost, low required concentration, and complete lack of injurious effects on fruit and foliage, para-chlorophenoxyacetic acid was found, during the season of 1948, to offer considerable promise as a material to induce parthenocarpy and, thereby, substitute for caprification of the Calimyrna fig (4). Commercial exploratory trials during the season of 1949 demonstrated the practicability of using this material as a substitute for cross-pollination by the fig wasp. The extent to which the industry adopts this practice depends mainly upon the demand by the consuming public for a fig that does not contain sclerified achenes ("seeds") and lacks the "nutty" flavor which characterizes caprified Calimyrna figs. Although the largest percentage of figs set in the 1948 investigation was obtained with an aqueous spray containing 60 p.p.m. of para-chlorophenoxyacetic acid (4), further information was desired on the range in concentration of this compound effective in promoting parthenocarpy and the thoroughness with which the spray should be applied. Tests with Sure Set, a proprietary material containing para-chlorophenoxyacetic acid, parafluorophenoxyacetic acid, and 2,4,5-trichlorophenoxyacetic acid were also made and will be discussed later. The commercial trials mentioned above enabled the periodic collection of samples large enough to make certain physical and chemical comparisons between induced parthenocarpic and caprified figs.