PRUNING THE DIFFERENT TREE FRUITS 259 



outward-growing branches. This type of pruning, together 

 with fertilization and good cultural practices, will cause a 

 stronger growth throughout the whole tree, the old spurs will 

 be invigorated, more blossoms will set, and larger numbers of 

 new spurs will be formed. 



It will be recalled from Chapter IV, 'The Growth of the 

 Tree and the Forming of Fruit Buds,^^ that fruit buds of the 

 sour cherry are producing laterally on one-year shoots and on 

 spurs. Short terminal and lateral growths 5 to 8 inches in 

 length usually form fruit buds at each node, and as a result 

 no leaf buds are available for developing fruit spurs. When 

 longer shoots (10 to 18 inches in length) are produced, fewer 

 lateral fruit 'buds and more spurs are formed. A tree with 

 numerous spurs has a much larger fruit-producing system, and 

 in the Northern regions buds on spurs seem to be more re- 

 sistant to winter freezing than those on shoots. Under such 

 conditions it can readily be seen why a heavier type of prun- 

 ing for increasing terminal and lateral growth, in order to 

 develop a large spur system, would be desirable. 



The Plum 



Although there are several different species of plums, the 

 chief species grown are the Japanese plums {Prunus salicina) , 

 the European plums and prunes {Prunus domestica) , and the 

 Damsons {Prunus insititia). The Japanese varieties usually 

 make a more spreading growth than the others, and come 

 into bearing earlier. 



The Japanese varieties usually bear more fruit laterally 

 on one-year wood, like the peach, than do the other kinds 

 of plums. Considerable fruit of all plums is borne on spurs. 

 These spurs are often quite short, causing the lateral buds 

 to appear in clusters in the Japanese plums. 



(a) Young Trees Should Be Pruned Rather Lightly, 

 Plum trees need very little pruning while young. The Japanese 

 plums are generally pruned by the open-head system, whereas " 



