PRUNING BEARING APPLE TREES 3 



trees were too limited to warrant conclusions. In general more libera! nitrogen 

 applications gave larger increases in net returns than did pruning. Pruning 

 cannot be regarded as a substitute for thinning as the former removes both good 

 and poor fruits, while in the latter some selection can be made. Profits depend 

 much upon high yields, and pruning, especially if rather severe, decreases yields. 

 However, Marshall does not recommend that bearing trees be left unpruned. 

 Dead and weak wood must be removed, and pruning may facilitate orchard opera- 

 tions such as spraying, thinning, harvesting, and cultivation, and keeps the trees 

 from becoming too high. 



HofMann 5 obtained considerably larger yields from unpruned trees than from 

 heavily pruned trees, and possible small increases from lightly pruned trees as 

 compared with unpruned trees. These experiments were carried on in Virginia 

 with York Imperial and Stayman. 



The reasons usually given for pruning bearing apples trees are well known to 

 all who deal with them. Among them are: pruning increases the average size 

 of the fruit; it facilitates spraying and lessens the amount of injury from insects 

 and diseases; it favors color development; it sometimes increases the size of 

 the crop; and it may promote tree vigor. The experiments here reported were 

 planned to help determine whether or to what degree these reasons are sound. 



Description of Orchards 



Trees from four orchard blocks have been under observation. Two are of com- 

 paratively young orchards, one contains middle-aged trees, and the fourth is 

 made up of old trees. 



Block A. — This is an orchard in which a pruning experiment with young trees 

 was conducted. This work has been previously reported. 6 Since it was terminated, 

 the trees that had not been pruned (except to remove suckers and water sprouts) 

 have been so continued. Therefore these trees have never been pruned since 

 they were planted as one-year whips in 1916. The other trees, which were pruned 

 in five different ways up to 1925, have all been moderately pruned each year. 

 The varieties included are Baldwin, Northern Spy, Rhode Island Greening, 

 Mcintosh and King. There were five trees of each variety unpruned and five 

 similar trees of each variety pruned in each of five different ways up to 1925. 

 In the spring of 1930 the trees of three types of pruning were removed on account 

 of crowding. 



Block K. — This orchard is Wealth) 1 , interplanted with several varieties. The 

 Wealthy trees were planted as fillers but have been retained and the other varieties 

 cut out. There were 144 Wealthy trees planted in 16 rows, 40 feet apart with 

 trees in the center of the squares, the other varieties bringing the planting distance 

 down to 20 feet. The orchard was planted in 1915 and the pruning experiment 

 started in 1921. It was cultivated with cover crops up to April 1928 when it 

 was seeded to timothy and Kentucky blue grass and has since been in sod. The 

 vigor of the trees since seeding varies from poor to good. The trees have tended 

 strongly to biennial bearing in recent years and have borne good crops. 



These trees were divided into four lots each distributed through the orchard. 



'HofMann, F. VV. Tabular biometrical presentation of pruning treatments with apple trees 

 Amer. Soc. Hort. Sci. Proc. 28:613. 1931. 

 6 Sha\v. J. K. Head formation in apple trees. Mass. Agr. Expt. Sta. Bui. 238. 1927. 



