PRUNING PRINCIPLES 117 



Goumy* states the buds on very vigorous trees may be transformed 

 into fruit buds by defoliation that is, the removal of the supporting 

 leaves from certain buds but not all the buds on the branch; how- 

 ever, he considers this operation very limited in its application and 

 not to be recommended for general practice. 



Fruit growers in England have long practiced summer pruning. 

 The consensus of opinion and experience of both practical fruit 

 growers and scientists, given some years ago, is that summer pruning 

 is uncertain in its effects, depending upon soil, climate, varieties of 

 fruit and time of operation, that specific objects may be accom- 

 plished by the process, but that the operation is of doubtful prac- 

 ticability. 



109. Summer pruning of apples. In a recent bulletinf Batchelor 

 and Goodspeed give the following condensed conclusions : Apple 

 trees, pruned to induce a spreading habit by cutting back the terminal 

 growth to lateral branches, produced a greater annual twig growth 

 than trees similarly pruned, except that the terminal growth was 

 untouched. Trees pruned during the dormant period and also dur- 

 ing the summer, produced a greater annual twig growth than trees 

 pruned during the dormant season only. Trees pruned during the 

 dormant season produced a greater total twig growth than the un- 

 pruned trees. 



Rubbing the water sprouts out of the center of the tree from 

 time to time during the summer, had little or no influence on crop 

 production. These shoots are removed much more readily and 

 cheaply, however, during this season. 



Trees pruned to a spreading form by cutting back terminal growth 

 to lateral branches, in the case of both Jonathan and Gano [the two 

 varieties experimented upon], averaged a smaller production to the 

 tree than trees allowed to assume a more natural upright growth. 

 The ratio of the total pounds of marketable fruit for the two va- 

 rieties during four years is 86 for Jonathan and 91 for Gano from 

 trees pruned to spread, as compared with 100 per cent each for 

 trees allowed to take natural shape. The summer-pruned trees 

 averaged less marketable fruit to the tree than either the winter- 

 pruned or the unpruned trees. 



The winter-pruned Jonathan trees produced more fruit than the 

 unpruned trees. The winter-pruned Gano trees produced less fruit 

 than the unpruned trees. Summer pruning in this orchard has 

 proved neither profitable nor successful in increasing crop yields. 



Although the investigation is only in its first stages, there seems 

 to be a correlation between regular bearing and summer pruning. 

 Tn the case of the Gano trees the most regular bearing trees were 

 the unpruned ones. Summer pruning throughout a period of two 

 months between the third week in June and the third week in 

 August produced much the same results. 



* Recherches sur les bourgeons des arbres fruitlers. Ann. Sci. Nat Bot. (Paris), 

 de Serie 1 : 135 to 246. 1905. 



v No. 140 Utah Agricultural College Experiment Station. 



