The influence of fungicides and gibberellin (A(4+7)) applications on russet control of 'Golden Delicious' apple fruit

Various fungicides, gibberellins (A(4+7)) and their mixtures were tested fo r the control of russet of 'Golden Delicious' apple fruit in the major appl e-growing area in Israel. Four foliar applications of captan, metiram, the strobilurins kresoxim-methyl, trifloxystrobin, azoxystrobin, or the polyoxi n B compound Polar from the green tip stage to the end of the petal fall st age gave similar reductions in russeting, compared with the controls, but n one eliminated it. Tank mixtures of the gibberellins (A(4+7)) Regulex and P erlan with captan, each at full rate, did not improve russet control, compa red with each component alone at the same rate. Similarly, both captan and trifloxystrobin, and the gibberellin (A(4+7)) Cytolin or their mixtures at full rates provided similar significant level of control of russet on fruit . Fruit in the upper part of the tree had significantly more russet than fr uit in the lower part of the tree, regardless of treatment applied. In addi tion, russet was more severe on fruits of trees grown in the west side of t he row, than those of trees grown on the east side. Data suggest that facto rs other than fungicides, which may act by reducing russet-inducing microor ganisms, may be involved in russet development.