Influence of 6-benzyladenine tank-mixed with boron, followed by mid-summer calcium plus copper sprays , on ‘Gala’ splitting and firmness.

Peryea, F.J. and Neilsen, G.H. (2013). "Influence of 6-benzyladenine tank-mixed with boron, followed by mid-summer calcium plus copper sprays , on ‘Gala’ splitting and firmness.", Acta Horticulturae (ISHS), 984, pp. 393-400.

Abstract

Gala’apple fruits are prone to splitting and softening, which may be exacer-bated by practices used to enhance fruit size. We evaluated two practices believed by some growers to be effective tank-mixing boron (B) with the plant bioregulator 6-benzyladenine (6-BA) to further promote the beneficial effect of the 6-BA on fruit size, and applying mid-summer calcium (Ca) plus copper (Cu) sprays to reduce splitting and to enhance firmness of the presumably larger fruit. The experimental trees were hand-thinned to commercial standard to reduce the effect of crop load on fruiting responses. The 6-BA, with or without added B, failed to influence fruit mass, red color, starch index, firmness, or splitting incidence. Following up the 6-BA+B treatments with six mid-summer Ca plus Cu sprays produced no beneficial effects on the fruit but did substantially increase fruit Cu concentration and unwashed leaf tissue concentrations of component elements (Ca, Cu, P, S, Zn, Mn) of the Ca plus Cu spray. With one exception, detergent- plus acid-washing of the leaves lowered the concentrations of these elements to background levels, suggesting that they were present as non-phyto¬active spray residues on the leaf surfaces. Only Cu remained elevated in the washed leaves. The Ca in the applied Ca product (an organically complexed CaO) did not appear to be phytoavailable. The results of the current study indicate that tank-mixing B with 6-BA applied for fruit sizing and applying mid-summer Ca plus Cu sprays do not improve ‘Gala’ fruit quality.

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