122 CALIFORNIA FRUITS I HOW TO GROW THEM 



RENEWING OLD TREES 



Improving and renewing trees by cutting back and grafting has 

 already been considered under the head of propagation. It is often 

 desirable to renew trees of a satisfactory variety, and this is done 

 simply by cutting back when the tree is dormant. Cutting back was 

 formerly done early in the winter, before the rise of the sap begins, but 

 more recently it has been seen that the exposure of large cut surfaces 

 for weeks or months before growth begins, results in drying and shrink- 

 age of the bark and checking of the wood, both of which are avoided ( 

 by amputation later in the dormant period or during the early part of 

 the growing season, In cutting back, of course, those stumps should 

 be left to support new branches which will secure the best balance and 

 symmetry in the new head. When the new growth starts there gener- 

 ally appear many more shoots than are desirable, and selection of the 

 best-placed and most vigorous should be chosen, the others either being 

 rubbed off in the bud or pinched back when a few leaves are put out. 

 In cutting back trees, the exposed trunk and branch stumps should be 

 wrapped in old sacking, or carefully whitewashed as protection from 

 sunburn. 



In removing large limbs it is desirable that the cut should be made 

 in the right place so as to secure quick covering of the scar with new 

 growth. Cutting so as to leave a long stub results in an unsightly 

 piece of dead wood on the tree, and this, in decaying, carries the decay 

 deep into the center of the trunk or branch. Cutting too close prevents 

 covering with the new bark, and also results in a hole in the branch. 

 Cutting just to the right mark, which is the outer edge of the little 

 collar or swelling which will be found at the base of all branches, 

 enables the wound to grow over quickly, and if the wound is properly 

 treated when cut, there will be no decay, and the wound will soon be 

 obliterated. 



In amputating large branches, an undercut with the saw should be 

 made first so that the bark shall not be torn as the branch falls. Another 

 good way is to saw off first at a distance from the final cut, and then 

 saw off smoothly at the right place when the weight is removed. 



Trees often become "hide-bound," as it is called. Especially in this 

 dry climate the bark gets dry and tough, therefore can not expand in 

 proportion to the growth of the tree, or supply the amount of sap neces- 

 sary for the demand. Slitting such trees here and there up and down 

 the trunk and main limbs with a sharp knife seems to have good effect, 

 for often in three months the cut opens half an inch, and a fine, clear 

 bark, with an increase of growth, results. On old trees, too, there is 

 often a growth of moss and lichens which should be removed. This 

 can be done by scraping off the rough, loose bark and spraying with 

 an alkaline wash, composed of one pound of caustic soda or potash to 

 six gallons of water. If scale insects are present, the lime, salt, and 

 sulphur spray should be used, as will be described in the chapter on 

 injurious insects. This will remove the parasites, give the trees a clean, 

 bright bark and contribute to their vigor. 



