Good Fruit Grower

February 2015

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18 FEBRUARY 1, 2015 Good Fruit Grower GROWING without branches B anchless, multileader trees open new windows for more efficient production, due to lower cost per unit of fruit, and/or higher prices that the orchardist receives per unit of fruit. Orchardists and researchers well know trees (especially apples) that are closely planted and arranged so that they intercept the optimum sunlight, improve productivity, and keep costs in check. Should canopies be vertical or angled? Both have merits. Orchardists usually decide according to locality, crop, experience, quality of labor available, advice from progressive orchardists and researchers, and whether the system can be mechanized. There are many systems that orchardists can use successfully. However, there is room for improving the bottom line with a modified system. One way is to use the multileader trees advocated by orchardists and researchers in several countries. Features of a branchless four-leader system are: —The architecture of the tree is simple with only a pri- mary structure of a short trunk with two or more leaders per tree that are dressed with short fruiting wood. —Branches are neither created nor manipulated. —The trees are closely planted and supported by a trellis to form canopies that are either vertical or angled. —The branchless leaders are neither basitonic nor acrotonic, meaning that branching is neither predomi- nantly toward the tip of the leader or the base. —The thin, two-dimensional canopy is uniformly filled with leaders. There are no gaps in the upper part of the canopy. —The system is easily mechanized. —At first, the roots are not restricted and push the trees to fill their spaces on the trellis as quickly as pos- sible, so they have a short vegetative phase. Later, when roots have filled their space and are then restricted, they help to control vigor of the leaders. —Vigor is equally divided over four leaders, and more easily controlled than in trees with two leaders. The rootstock controls vigor less. —The crop can be accurately targeted, monitored and managed, because all four leaders have the same num- ber of fruit. During winter, bud counts help to determine the intensity of pruning needed to establish the crop load for the coming season. —Unskilled labor can easily learn to prune the trees and to thin and harvest the fruit. —Some leaders can be used as pollinizers; this improves the pollination strength, and individual pol- linizer trees are not needed. —The thin canopies improve air circulation, allow good spray coverage, reduce spray drift, and need less spray material per acre. —Leaders can be renewed when they become less productive. One leader is removed at the time and is replaced by a new leader. —Nursery trees do not need to be double-budded, which is a patented method and is costly. —Training of multileader trees preferably starts in the nursery, when they are headed to force development of side shoots. After the trees have been planted in the orchard, suitable forks are selected and cut back. The trees then generate several shoots out of their heads. Four shoots are then gradually selected to make sure that the future leaders are uniform in size and thickness. —After they are planted, nursery trees are headed, which helps prevent transplant shock. —Infection by fire blight can be detected early, so that the trees will not be damaged much. When an infected leader is removed in spring or early summer, a new shoot soon replaces the infected leader. —In research, multileader trees can simplify statisti- cal designs of experiments, because individual leaders rather than whole trees, can be used for treatments. —Many temperate, subtropical, tropical and ultra- tropical fruit crops adapt well to the branchless mul- tileader system, making it one of the most versatile state-of-the-art production systems. Manage from ground Open-V systems, such as the Open Tatura, incorpo- rate all of the above features. As well, the canopy of the Open Tatura has a higher surface area that orchardists can manage from the ground, whereas (at the same Figure 4 This 20-month- old pear tree on seedling rootstock of Pyrus calleryana is part of an Open Tatura with four leaders. Figure 1 The two inner shoots of this pear tree were not cut back, so after 20 months of growth the two inner leaders show disproportionate vigor and size. Figure 2 The Open Tatura trellis has been prepared for each tree to grow four leaders. Small plastic clips have been placed on the high-tensile wires 500 mm (20 inches) apart. Strings are then tied along the clips. Shoots are tied to the strings with a Max Tapener, to ensure uninterrupted growth of the leaders. The two inner shoots are cut back to give the two outer shoots a good head start. This diagram shows only one side of the trellis. Figure3 Final sequence of leader development. Retarded growth of the two inner shoots has created four uniform leaders. Figure 6 Black Amber plums. Fruit is evenly distributed along each leader. The branchless multileader system offers improved efficiency. by Bas Van den Ende Horticulture Figure 5 It takes much labor to manipulate branches. These nine- month-old Pink Lady trees on Malling-Merton 106 on Open Tatura are carefully trained to ensure early and high sustainable yields. The branchless multileader system is a simpler (and cheaper) alternative.

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