
%0 Journal Article
%A Jones, K. M. 
%A Bound, S. A. 
%A Summers, C. R. 
%A Oakford, M. J. 
%T Preliminary examination of thinning strategies on young &#8216;Jonagold&#8217; and &#8216;Pink Lady&#8217; apples
%J Australian Journal of Experimental Agriculture
%D 1997/05/21
%V 37
%N 3
%P 377-382
%K 
%R https://doi.org/10.1071/EA96088
%U https://www.publish.csiro.au/paper/EA96088 
%X Summary. Strategies were examined for thinning 5-year-old apple trees of &#8216;Jonagold&#8217; and &#8216;Pink Lady&#8217; with chemical thinners. Both cultivars were left unthinned (control), hand-thinned at 20 days after full bloom (DAFB) or chemically thinned. The chemical treatments consisted of full bloom (FB) sprays of naphthalene acetic acid (NAA) at 2.5, 5 or 10 mg/L or ethephon at 25, 50 or 100 mg/L or combination treatments of 2.5, 5 or 10 mg NAA/L at FB followed by 50 mg ethephon/L at 7 DAFB. In addition 5 mg NAA/L or 50 mg ethephon/L were followed by 150 mg CyLex/L (6-benzyladenine, Abbott Laboratories) at 20 DAFB. Neither NAA, ethephon alone or NAA followed by ethephon were effective at the 2 lower concentrations. The highest level of NAA with ethephon did some thinning of &#8216;Pink Lady&#8217; but overthinned &#8216;Jonagold&#8217;. The CyLex combination treatments were the most effective. Combining NAA and CyLex did not thin enough to increase fruit size in &#8216;Pink Lady&#8217; and slightly overthinned &#8216;Jonagold&#8217;. The most effective treatment of ethephon and CyLex removed about half the crop load compared with the control for both cultivars. This resulted in a 29% increase in fruit weight and a 48% increase in fruit size for &#8216;Jonagold&#8217;. &#8216;Pink Lady&#8217; increases were less, being 16% for fruit weight and 38% for fruit size. All mean fruit weight and size outcomes for the ethephon&#8211;CyLex treatment exceeded provisional targets. The ethephon&#8211;CyLex combination had important fruit quality outcomes other than fruit weight and size. Fruit soluble solids were increased by this treatment by 10% for &#8216;Jonagold&#8217; and 6% for &#8216;Pink Lady&#8217; and fruit firmness by 11% for &#8216;Jonagold&#8217; and 5% for &#8216;Pink Lady&#8217;. The overall results for the ethephon&#8211;CyLex combination were most encouraging for both cultivars. Further work is required to substantiate these results. 
