258 



PRINCIPLES OF PLANT CULTURE 



427. Pruning for growth may be performed : 



(a) By removing a part of the branches, thus reducing 

 the number of growing points and the surface exposed to 

 evaporation. Plants that are not making satisfactory 

 growth, through feeble root action, may often be in- 

 vigorated by this treatment, which is especially useful 

 in trees recently transplanted or 

 weakened by overbearing. 



(b) By suppressing reproduction. — • 

 When growth is desired, it is often 

 advisable to prevent the development 

 of flowers. Newly planted straw- 

 berry, raspberry and blackberry 

 plants usually make better growth 

 the first season if the flower-buds 

 are picked off. The removal of 

 flowers in the potato plant tends to 

 stimulate the growth of tubers, es- 

 pecially in varieties that form seed. 

 The removal of flower-buds from 

 cuttings in the propagating bed en- 

 courages the formation of roots. 

 Topping tobacco and rhubarb plants 

 (416) causes the leaves to grow 

 larger, and in onion plants stimulates growth of the 

 bulbs. De-tasseling corn encourages growth of the ears 

 (416). Thinning fruit on plants that incline to overbear 

 causes the remaining fruits to grow larger (159, 416). 



428. Pruning for flowers or fruit. — Since checking 

 growth tends to stimulate the formation of flower-buds 

 (134), we encourage flowering in plants that incline to 

 luxuriant growth, by pruning, which tends to check 

 vigor. This may be accomplished : 



Fie. 166. — Branches 

 of fruit tree tied to- 

 gether by a graft 

 formed of twisted 

 twigs. 



