Response of Bosc and Cold Snap™ pears to thinning with NAA, 6-BA, ACC and S-ABA

Adjusting the crop-load of European pears [Pyrus communis L.] by hand thinning is currently required to ensure marketable size of most cultivars grown in Ontario. The benefits of chemical thinning pears and their effect on fruit quality and fresh-market returns was investigated in a three-year study where a series of foliar chemical thinning sprays was applied during the 10-mm fruitlet stage to Bosc and Cold Snapâ ˘ pear trees growing in commercial orchards in the Niagara Peninsula, Ontario. Treatments included an untreated and hand-thinned control, and two concentrations each of 6-benzyladenine (6-BA; 75 mg L-1 and 150 mg L-1), naphthalene acetic acid (10 mg L-1 and 20 mg L-1), 1-aminocyclopropane carboxylic acid (150 mg L-1 and 300 mg L-1) and s-abscisic acid (s-ABA; 150 mg L-1 and 300 mg L-1). Overall, all thinning products reduced crop load at least once in the three-year study, although this varied by year and cultivar. Higher concentrations were more effective than lower concentrations. Napthalene aceditic acid (both rates), 150 mg L-1 6-BA and 300 mg L-1 s-ABA were most consistent. Since the crop load of control trees was not heavy, minimal hand thinning was required and all thinning treatments reduced crop value compared with the untreated trees. There were minimal effects on starch hydrolysis, soluble solids, fruit firmness and skin colour at harvest.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author