DAMINOZIDE, ROOT PRUNING, TRUNK SCORING, AND TRUNK RINGING EFFECTS ON FRUIT RIPENING AND STORAGE BEHAVIOR OF MCINTOSH APPLE

A midsummer foliar daminozide (DZ) application (750 mg a.i./liter) to 'Macspur McIntosh'/M.7 apple trees (Malus domestica Borkh.) reduced preharvest drop and retarded flesh firmness loss and starch hydrolysis when tested at harvest; DZ also reduced fruit ethylene production at harvest and after 19 weeks of storage at 0.5C. Root pruning at full bloom (May) resulted in increased soluble solids concentration (SSC) and firmer flesh and less starch hydrolysis at harvest, but not consistently each year. Full-bloom root pruning reduced the incidence of stem-cavity browning and brown core, but again not each year. Full-bloom root pruning did not influence ethylene evolution at harvest but did reduce post-storage ethylene evolution in two of three seasons. Full-bloom root pruning generally was less effective than DZ in altering fruit behavior, while root pruning later than full bloom had virtually no effect. Trunk scoring or ringing increased SSC and retarded loss of flesh firmness before harvest and following storage, but had little effect on starch hydrolysis. Scoring or ringing decreased incidence of some disorders and reduced post-storage ethylene evolution, although these treatments had little effect on ethylene production at harvest. Trunk scoring influenced some fruit characteristics more strongly than DZ. Fruit size was not affected by any treatment in any year. Chemical name used: butanedioic acid mono (2,2-dimethylhydrazide) (daminozide).