236 PRINCIPLES AND PRACTICE OF PRUNING 



ground. Sprouts or grafts may be used to form a new 

 top. The sprouts may be budded when large enough. 

 When the trunk seems unhurt it may be left to develop 

 a new top, only the injured parts being removed. Most 

 pruners leave too mueh of the old wood. In such cases 

 the heart wood decays leaving only a thin cylinder of 

 li^'ing wood. This becomes so weak that the loaded 

 branches break unless propped or wired, processes which 

 are both costly and unsatisfactory. 



188. Pruning and shaping orange trees. — Accorfling to J. W. 

 Mills,* the tendency of young trees of Washington Navel and some 

 other varieties to assume a drooping habit when making a vigorous 

 g owth is because the soft shoots are unable to support the weight 

 i>f the large, heavy leaves. Even trees that have been long in bear- 

 ing will be benefited by pinching back every branch that takes too 

 vigorous an upward growth. This pinching process is especially 

 necessary with trees one to five years old. 



188a. Pruning bearing trees.— An upright tree has a decided ad- 

 vantage over a drooping one when loaded with fruit. The crop 

 is borne with less breakage of limbs, and not so much fruit is in- 

 jured by the wind. After the trees are in full bearing, there seems 

 to be no pruning that will promote the health of the trees or im- 

 prove the crop other than cutting out limbs that project abruptly 

 from the side, or those that make a sudden skyward growth, and 

 the constant trimming out of dead or stunted wood found on the 

 inside of the trees. 



If too close, the branches should be thinned out from the inside 

 until the sunlight has had free access. This does not make any 

 noticeable difference in the appearance of the tree, but makes it 

 bear fruit on the inside. Such fruit is safe from sunburn and frost 

 and packs as "fancy" grade. By early attention to pruning, the 

 trees need never be allowed to grow too close in the center. 



189. Renewal of tops. — Some groves of old orange trees do not 

 respond to even the best treatment the owners can give them. 

 Under such circumstances, the most effective way to stinuilate new 

 life and vigor is sometimes to remove the entire top, leaving enough 

 of each of the main limbs to distribute equally the suckers that will 

 afterward make the new top of the tree. If the tops are only 

 thinned out and but partially cut back, there will be a proportionate 

 amount of feeble growth and a corresponding lack of productiveness. 



."Xn old orange tree will rapidly produce a new top, even when cut 

 back to a mere stump. It is soon in a condition to bear again at 

 its full capacity. When the roots are healthy and the soil is prop- 

 erly cultivated and fertilized, the orange tree appears able to produce 



* California Experiment Station Bulletin 138, 



