This section is from the book "Commercial Gardening Vol3", by John Weathers (the Editor). Also available from Amazon: Commercial Gardening, A Practical & Scientific Treatise For Market Gardeners.
In many market gardens there are either walls or fences that may be, and are, utilized for the cultivation of some of the choicer or more tender varieties of Pears. The trees may be trained on the walls in various ways, either as single oblique cordons or as double oblique cordons (fig. 350); in the forms of single or double columns (fig. 351), shapes useful for the butt end of walls; or they may have the branches trained horizontally, or radiating like a fan.
Fig. 350. - Double Oblique Cordons.
Fig. 351. Double Coruuu.
Whichever method is adopted means more expense in cultivating than trees grown as bushes, half-standards, pyramids, or standards. The extra expense will be entailed in tying, nailing, summer pruning and pinching, and also in winter pruning, and the only set-off against this expense would be in having particularly fine fruits that would realize something like one-half or a quarter of the big prices at which they are retailed at the west-end shops.
In market gardens sufficient attention is not given to the proper pruning of fruit trees on walls. The men employed are usually unskilled in the art of gardening, and they often know little or nothing as to the difference between fruit buds and wood buds on a tree. The result is often deplorable. The best flower buds are destroyed, and numerous sappy growths take their place season after season. The natural result is no fruit, waste of money, labour, time, walls, nails, shreds. For these troubles the weather, frost, foreign competition, and all sorts of things except the real cause - the ignorance of the pruner - will be blamed, and fruit growing on walls for market purposes will be voted a rank failure. It would be found more economic and certainly more profitable to employ trained gardeners in all matters appertaining to the pruning and cultivation of fruit trees, and more especially when grown on walls.
To keep Pears in a good fertile condition on walls, attention must be given to pinching back the young growths during the summer months. When 1 ft. or 18 in. in length, the tips should be pinched out with the finger and thumb, or the shoots may be cracked and half-broken through, so that they hang down. This stops further increase in length, without causing the basal buds to start into twiggy shoots, but rather to remain dormant and gorge themselves with the food that has been elaborated by and in the leaves. Such shoots are shortened back to two or three buds in winter. In the case of Pears, Apples, Plums, and Sweet Cherries, the fruit spurs mostly form on branches from two to seven years of age, and may be distinguished even in the summer months by their short stumpy growth, and by the cluster of leaves around them. [j. w.]