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Shock of the new

posted 23 Aug 2012, 04:12 by Rosemary Russet   [ updated 6 Sept 2012, 10:17 ]

Coming up for air from the depths of funding application hell, the lush greens of our trees, now dappled with ripening red fruits, are a soothing sight for sore eyes.  Much moisture plus the warmer temperatures of summer are the ideal conditions for the exuberance of leafing shoots on established trees (and the supercharged growth of grasses and ‘weeds’).  It looks like there’ll be plenty of summer pruning to do.  Most of our apple and pear trees were planted c.2000, and have now settled into their mature forms.  Each tree has a framework of strong branches with each branch having networks of fruiting spurs or tips.  A summer growth spurt of leafing shoots allows the tree to maximise the intake of sun and photosynthesis through fast-growing broad leaves.  These young shoots, however, do not have fruiting buds on them.

Orchard keepers enter a semi-symbiotic relationship with fruiting trees.  Left to their own devices apples trees produce small-ish fruits.  Putting the energy into larger fruit, while ‘costly’ to the tree, is a result of natural selection (up to five to eight thousand years ago) and human selection (since then)*.  Pruning out the new growth does two things.  In a younger, developing tree (and on younger growth), cutting back the leafing shoots sends a chemical message that creates fruit buds at the base of the shoot.  On established trees it returns the energy of the tree to mature, fruiting wood, while also opening the canopy up to more light and air, helping to ripen fruit and reduce diseases like scab and canker.

Day length also influences the energy cycle of trees.  We wait until at least two months after mid-summer before beginning to prune the already harvested early-fruiting trees.  This later start makes more sense in the mild climate of Southwest England.  In recent years we’ve tended to follow a pattern of pruning after harvest.  The leafy shoots on trained forms (cordon, fan, espalier) seem to give some protection against bird and other damage, though if they shade out the sweetening sun it’s time for a trim.

* For more information on the rise of the domestic apple see: The Story of the Apple by Barrie E. Juniper and David J. Mabberley, published 2009.