HOW HEAVILY TREES SHOULD BE PRUNED 229 



(c) Prune Old Bearing Trees More Heavily, Old bearing 

 trees somewhat low in vigor generally respond better to moder- 

 ately heavy pruning than to light pruning. The tops of such 

 trees gradually become filled with numerous branches which 

 are thickly set with old and weak spurs. Relatively little 

 new spur or terminal growth occurs, and the leaves are often 

 small and yellowish in appearance. The buds on the spurs 

 open into a whorl of leaves each year, but very little extension 

 growth is made. The wood of such trees gradually becomes 

 packed with carbohydrates in proportion to nitrates, and 

 such trees approach the non-vegetative and unfruitful class 

 described in Chapter IV. Either many of the fruit spurs 

 cease forming fruit buds, or, if buds are formed, many of 

 the blossoms fail to set. 



With such trees, moderately heavy pruning or much heavier 

 applications of nitrogen fertilizers have a decidedly invigorat- 

 ing effect. If larger amounts of fertilizers are not added, 

 heavy pruning will be especially beneficial. The pruning 

 should consist primarily of making numerous small cuts 

 equally distributed over the entire tree, so that all parts will 

 be invigorated. The lower limbs, especially, should- be well 

 thinned out and in some trees it will pay to head back lightly 

 an occasional slender, weak limb to an upward growing 

 branch. An attempt should be made to keep these lower 

 limbs growing and fruiting as well as those in the upper 

 parts of the tree. The ends of the upper branches, where they 

 are getting too high, should also be headed back to good 

 laterals. This will tend to lower the tops and stimulate 

 growth in the lower as well as upper branches. 



As a result of removing numerous small branches contain-^ 

 ing large numbers of spurs and buds, the amount of carbohy-^ 

 drates will be reduced and more water and nitrates will be 

 made available for each of the buds left. Terminal growth 

 becomes longer, and those spurs which remain, including many 

 which have not borne for years, make a longer growth, have^ 

 larger and greener leaves, and form fruit buds. 



