Efficiency of fruitlet thinning in ‘Granny Smith’ apples by use of metamitron

Abstract

In this paper the results of chemical fruit thinning in the apple cultivar ‘Granny Smith’ carried out with the herbicide Brevis® containing 150 g kg-1 of metamitron as the active ingredient are reported. In two treatments, the effect of this compound was enhanced by NAA (1-naphthaleneacetic acid). This study was conducted in a commercial apple orchard of PIK “Južni Banat” located in Bela Crkva (Serbia), in two consecutive years (2013, 2014). The planting distance was 3.3×0.8 m (3878 trees ha-1) and trees were trained as slender spindle. Brevis® was sprayed when central fruits in the clusters were 12-14 mm in diameter. Applied treatments in ‘Granny Smith’ were as follows: control, 150, 188, 225, 150 mg L-1 of metamitron + 5 mg L-1 NAA and 225 mg L-1 metamitron + 5 mg L-1 NAA. Spraying volume was 800 L ha-1 in all applied treatments. Metamitron expressed a positive influence on crop load in both investigated years. Treatments containing metamitron alone provided large yield consisting of a high percentage of first quality fruit. The effect of metamitron could be enhanced by mixing with NAA.