"MINIMAL PRUNING" IN FREE SPINDLE BUSH PEACH TREES TO AVOID AN UNPRODUCTIVE PERIOD

Abstract

In Italy the “minimal pruning system” (a definition derived from the grapevine pruning technique) is generally utilized in peach orchards. One of its main rules is to initially obtain a “free spindle bush” shape, avoiding cutting back the scion at planting time but using lateral shoots to form future fruiting branches. This experiment involved a comparison of three high density peach plots of 0.5 ha each (with 1,500, 1,100 and 1,100 trees/ha), two varieties (‘Big Top’ and ‘Magique’) budded on GF677, that were trained until the 4th year, according to three “minimal pruning techniques” applied for the free bush system. The trees were converted to a proper “spindlebush” trees between the 3rd and 4th year and resulted in: 1) equilibrated minimal pruning, practiced during Winter and Summer; 2) reduced pruning time, through reducing the number of pruning cuts, utilizing several temporary fruiting branches (4-6/tree) and pruning only in Winter; 3) further reduction of the number of cuts (time) and then equilibrating the load of fruit with thinning and pruning, leaving more fruiting branches (up to 6-10/tree) in Summer. The “free spindle bush” at a density of 1,500 trees/ha performed very well when an equilibrated method of pruning was applied (yield of 18-20 kg/tree/yr with ‘Big Top’ and 55-64 kg/tree/yr from the 2nd to the 4th year with ‘Magique’, corresponding to a cumulative yield of 192 t/ha up to the 4th year. A further reduction of the pruning time was achieved in plots 2 and 3. By utilizing the production of older wood (branches of 2-3 years) the ‘Big Top’ trees achieved a higher yield (from 32 to 46 kg/tree/yr), but ‘Magique’ yields stayed the same. The most significant result of the highest equilibrated HDP system (1,500 tree/ha) was the size of the ‘Big Top’ fruit: 57% of the fruits were classified as size A and AA, versus 17-21% in the other two systems. With ‘Magique’ 40% of fruits were sizes A-AA almost comparable with the other two systems. Between the two systems which used old bearing wood, the performance was highest and better (for size) on the second plot (1,100 trees/ha) where the Winter pruned old branches were generally no more than 4-6/tree and therefore most of the best fruiting shoots were maintained on the trees.