THE MACADAM 1 A M T IN HAWAII 9 
Other related and possibly more resistant species not now utilized 
may then be brought into use as rootstocks. 
A number of air layerings w r ere successfully made at the station. 
Branches about 1 inch in diameter and 4 feet in length were girdled, 
the bark being removed to the sapwood. The wound was then sur- 
rounded with a sterilized mass consisting of equal parts of sphag- 
num moss and rich potting soil held firmly in place w r ith burlap and 
string. For further security the mass was surrounded with a tin can 
cut and spread to fit snugly and bound in place with wire. Well- 
rooted branches were ready to be cut off and potted as new trees in 
30 to 60 days. Air layering of the Macadamia may be accomplished 
in the same way as is done with the litchi, and with about the same 
degree of success (13, p. 7). (Fig. 5.) 
Inarching was found to be difficult, especially where a high scaf- 
folding had to be used to bring the rootstocks to the desired scion 
branches of large trees. Root sprouts and basal sprouts of orchard 
trees were more easily inarched. Unions 6 to 15 inches long proved 
to be the most satisfactory. In making these unions the bark and 
wood one-half inch wide were cut away from the side of both stock 
and scion at the point of union, and the two exposed surfaces were 
bound tightly together with raffia. The entire union was then sealed 
with a coat of lukewarm liquid paraffin. These inarches were sepa- 
rated from the parent tree after 28 to 30 days. The top of the seedling, 
beginning just above the union, and the part of the scion just below 
the union were cut off, and the exposed surfaces of the newly formed 
tree were covered with a protective coat of grafting wax. 2 The 
foliage surface was then reduced by clipping off about half the 
number of leaves. Nineteen days after separating the new tree from 
the old one, a number of buds began to lengthen into preliminary 
branches for forming the top. 
In the grafting experiments several kinds of unions were tried, 
1-year-old seedling stock being used for the purpose. The diameter 
of stem of these seedlings at the point of union varied from three- 
eighths to five-eighths inch. The kind of grafts tried were shield 
budding, whip graft, wedge graft, and side-tongue graft. None 
of the first three kinds of grafts grew, but a number of the side- 
tongue unions were successful. In making the side-tongue grafts the 
scion of both the desirable variety and the seedling stock were of 
about the same diameter and vigor of growth. The material varied 
from five-sixteenths to one-half inch in diameter. (Fig. 6.) The 
seedlings were grown in sterilized soil in tin containers or earthern 
pots and varied in age from 8 to 15 months. The wood was fairly 
hard, and it was necessary to use a strong, thin-bladed grafting 
3 The following recipe for a sporial grafting wax for use in the Tropics has been used at 
the station for several years with excellent results : To 1 part tallow by weight add H 
parts beeswax and 4 parts resin. Melt the tallow in a suitable iron kettle over a slow fire ; 
then add the beeswax. As soon as the mixture begins to boil add the resin gradually, 
stirring continuously until it melts. Continue the boiling for live minutes, then remove 
the kettle from the stove and pour the liquid through cheesecloth into a large container 
of cold water. When the mixture has thoroughly cooled, work it with the hands until 
it becomes tough and doughy. Thorough cooling is very important to prevent lump 
formation. Kneading may be difficult at first, hut becomes comparatively easy after a few 
moments. To prevent the was from adhering to the hands, grease them slightly with 
tallow. A- soon as the wax assumes a creamy, silken color it may be worked into rolls 
about 2 inches in diameter and .1 inches in length, then wrapped in waxed paper. The 
wax is then ready for immediate use. or it may be stored for future use. If it hardens, 
knead in a very small amount of tallow. 
71015°— 20 2 
