PRUNING FRUIT TREES 



Special Bulletin No. 118 



BY ROY E. MARSHALL 



Most fruit growers will agree that tree growth and fruit production are 

 regulated to a considerable extent by pruning practices, but there is much 

 confusion as to the amount and kind of pruning that should be employed to 

 give the desired results. Experiment Station investigators are gradually 

 working out various phases of the pruning problem, but it will probably be 

 many years before definite rules can be formulated relative to the training 

 and pruning of all kinds and types of fruit trees. 



Yet, while these problems are being solved, trees must be pruned. It is 

 the main purpose of this bulletin to present some of the underlying principles 

 which the fruit grower should constantly keep in mind, and to show how these 

 principles may be applied to such trees as are commonly found in Michigan. 



SOME GENERAL I'RINCIPLES AND PRACTICES 



Throughout the discussion of pruning practices certain terms are used 

 more or less frequently, and it it well that an understanding be had of these, 

 together with the general principles involved. Again, certain practices are 

 applicable, in a general way, to all kinds of deciduous fruit trees, and these 

 may be briefly discussed before taking up more detailed consideration of the 

 handling of specific kinds of fruit trees. 



Thinning — The removal of an entire branch, limb, twig or spur is referred 

 to as thinning or "thinning out." Thinning results in a less crowded con- 

 dition throughout the tree, and it usually permits a greater amount of light 

 and a freer circulation of air in the interior portions. This kind of pruning 

 generally encourages the formation of fruit spurs and discourages the de- 

 velopment of lengthy side branches or laterals. It favors the development 

 of an extensive fruiting system, but continued thinning with some kinds and 

 varieties of fruits eventually leads to the formation of wide-spreading or 

 rangy trees that are expensive to handle and that are unable to carry their 

 crops without artificial supports. 



Heading — When the tip or any larger portion of a branch is removed, the 

 process is known as heading or "heading back." This type of pruning is 

 practiced when branches are growing out of bounds; when one part of the 

 tree is growing more rapidly in proportion to the tree as a whole than is de- 

 sired; to encourage the development of the framework branches of the tree at 

 such points as they are desired, and to avoid a rangy type of growth. The 

 heading back of a vigorous shoot usually results in the formation of several 

 strong-growing lateral shoots and few fruit spurs the succeeding year. Hence, 

 it promotes the formation of a compact head. In other words, heading back 

 has more to do with the development of form of tree than with the develop- 



