116 PRINCIPLES AND PRACTICE OF PRUNING 



So far as the writer knows, no definite experiments have 

 been tried to settle whether such trees are as productive as 

 others not so treated, but grown under as nearly identical 

 conditions as can be secured. One conceded advantage 

 shortening-in frequently has: when judiciously perfomed 

 it tends to early maturity of the trees and consequently 

 precocity of bearing. This, however, finds its chief applica- 

 tion in amateur practice; for commercial use it is of com- 

 paratively minor importance. 



107. Pruning at various seasons. Stimulation of wood growth 

 does not necessarily mean increase in the total mass of the trt-r. 

 From their studies of this question, the Duke of Bedford and Pick- 

 ering* have concluded that hard pruning does not ultimately re- 

 sult in a larger tree than does light pruning. In later experiments t 

 they found that the less a tree is pruned the greater is its w< >cl 

 growth, except in the case of old trees, on which the amount of 

 wood is increased by hard pruning; the hard pruning is antagonistic 

 to fruiting, this rule applying to both young and old trees. 



108. Summer pruning experiments performed by Drinkarcl, at 

 the time the fruit buds began to form, stimulated the development 

 of fruit buds. These experiments give some evidence on the prop- 

 osition, often expressed by horticulturists and practical fruit 

 growers, that summer pruning increases the fruitfulness of apple 

 trees. No doubt the degree of increase in fruitfulness resulting 

 from summer pruning bears direct relation to the condition of 

 the trees, the season and the time and severity of the operation. 

 But the physiological principle involved is not clear. It is obvious 

 that severe summer pruning reduces the foliage area, interfering 

 with transpiration and photosynthesis. The balance between the 

 root system and the branch system is suddenly disturbed. The 

 nutrition of the various organs in the tree is changed' in some <K- 

 gree by summer pruning. 



Quinn,^: who has described the various methods employed in 

 summer pruning disbudding, pinching, thinning, heading ii>. and 

 fracturing or twisting of branches found that these operations are 

 effective in greater or lesser degree for conditions in Australia. 

 Dickens** found from careful experiments that summer pruning 

 gave better results than pruning during the dormant season. l'>y 

 means of summer pruning, he was able to induce fruitfulness on 

 10-year-old apple trees which had previously borne very little fruit. 



* Woburn Experiment Fruit Farm, Second Report, 1900. 

 t Ibid. Seventh Report, 1907. 



Technical Bulletin 5, Virginia Experiment Station. 

 J Jour. Agr. and Ind. South Australia, Fig. 3: 368 to 378. 1899. 

 ** Kan. State Agr. College Exp. Sta. Bui. 136. 



