ISHS Acta Horticulturae 636: XXVI International Horticultural Congress: Key Processes in the Growth and Cropping of Deciduous Fruit and Nut Trees
COMPARISON OF NEW BLOSSOM THINNERS FOR APPLES UNDER CONDITIONS OF INTERMOUNTAIN WEST OF THE UNITED STATES |
| Authors: | E. Fallahi, B. Fallahi |
| Keywords: | 1-naphthyl-N-methylcarbamate, naphthaleneacetic acid, ammonium thio-sulfate, hydrogen cyanamide, endothalic acid, perlargonic acid, sulfcarbamide, Malus domestica Borkh., postbloom |
| Abstract:
Blossom thinners are caustic and reduce fruit set by damaging different flower parts, including anthers, stigma, style, and pollen tubes, and thus prevent fertilization. Elgetol (sodium dinitro-ortho-cresol (Elgetol, 19% a.i.) was previously used for blossom thinning in pome fruit. It was removed from the market in 1989 because of the high cost of re-registration. Elgetol’s loss renewed research efforts to find blossom thinners with similar modes of action. Effects of various rates and/or timings of Dormex, ammonium thiosulfate (ATS), Endothal, and Wilthin on blossom thinning (fruit set), fruit quality, and yield of ‘Delicious’, ‘Law Rome’, ‘Fuji’ and ‘Jonathan’ apples (Malus domestica Bork.) were studied. All of these chemicals reduced the fruit set, with higher concentrations being more effective. Double application of these chemicals often resulted in more blossom thinning than a single application. Double application of ATS at a rate of 15 mL L-1 or a single application of this chemical at a rate of 25 mL L-1 resulted in satisfactory levels of thinning in ‘Fuji’ apple. Double application of ATS at a rate of 25 mL L-1 resulted in excess thinning and is not recommended for apples. A single application of Dormex at rate of 3.12 mL L-1 significantly reduced the fruit set of ‘Law Rome’. Double application of Endothal caused fruit marking. | |
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