8 BULLETIN 49, HAWAII AGRICULTURAL EXPERIMENT STATION. 



Rough lemon seedlings have been employed by horticulturists for 

 some years to meet the need for strong rootstoeks for grafting pur- 

 poses. The main development of this variety has been toward the 

 production of vigorous and resistant rootstoeks. The fruit of the 

 rough lemon is rated of poor quality on account of its coarse, thick, 

 rough skin. 



The sour-orange stock is produced from seeds of the wild sour 

 orange which now grows in abundance in parts of Florida. Its 

 greatest value lies in its resistant rootstock. Results obtained from 

 experiments indicate that it has about the same value as the rough 

 lemon for propagating purposes. 



Pomelo seedlings, or what are commonly known as grapefruit 

 seedlings, make vigorous stock on which to graft the lime. 



The shaddock, a fruit of oriental origin, also makes a strong and 

 rapidly growing stock for citrus in Hawaii. 



Scions should be selected only from vigorous and prolific trees the 

 fruit of which is known to have a combination of the best qualities 

 that can be found. They should be about three-sixteenths inch in 

 diameter and of green fruit-wood possessing healthy buds, which 

 have not begun to swell with growth. 



Of the several forms of union such as shield-budding, bark, side, 

 and whip grafting, that of bark grafting is best. To effect this union 

 the stock should be cut off almost at right angles to the vertical axis 

 and made smooth. A downward slit should be made 1-J inches long, 

 beginning at the top and extending through the bark, to permit of its 

 spreading when the scion is inserted. As soon as the scion is cut the 

 lower portion should be beveled for inches and the flattened end 

 inserted in the stock between the bark and the sapwood so that the 

 cambium edges will be in proper contact. The union should then 

 be firmly bound with cotton twine or moist tying raffia, and the cut 

 surface sealed with grafting wax to keep out insects, shed water, and 

 prevent the delicate tissues from drying out. 



When shield-budding is practiced the shield should be put into an 

 inverted T-shaped incision made in the bark of the stock several 

 inches above the ground. It should then be pushed down until the 

 cambiums are in proper contact, firmly tied in place, and wound with 

 waxed tape for protection. Care should be exercised to raise the bark 

 of the stock without injuring the cambium. The foliaged top of the 

 stock, or a portion of it, should be left standing until the bud has 

 made a growth of several inches. It should then be severed from the 

 stock close to the bud with a slanting cut. The waxed tape should 

 be removed about six days after the operation and the binding string 

 several days later. 



Experiments which were made with bark grafting and shield 

 budding at the experiment station showed the former method to be 

 the better of the two in giving a strong union and an early upright 

 growth. 



The growth of grafted trees may be continued in gallon containers. 

 The young trees should be exposed to full sunlight so that they will 

 become hardy preparatory to being set permanently in the orchard 

 or home yard. At the end of 10 or 12 months they should be 12 or 

 15 inches high. 



