6 BULLETIN 334^ U. S. DEPARTMENT OF AGRICULTURE. 
berries serve the same purpose admirably. Oak leaves raked, stacked, 
and rotted for about 18 months Avithout lime or manure are also good. 
The leaves of some trees, such as maples, rot so rapidly that within a 
year they may have passed from the acid condition necessary for the 
formation of good peat to the alkaline stage of decomposition, which 
is fatal to blueberry plants. Even oak leaves rotted for several 
years become alkaline if they are protected from the addition of new 
leaves bearing fresh charges of acidity.^ The much decomposed peat 
in the submerged lower layers of deep bogs, such as is used for fuel 
in Europe, is not suitable for blueberry- soil mixtures. 
TUBERING. 
By ordinary methods, cuttings of the swamp blueberry have been 
rooted onl}^ in occasional instances. Successful special methods, how- 
ever, have now been devised for these plants. Wild stocks of the 
swamp blueberry vary greatly in their response to propagation by a 
particular method, and it is likely to prove true that one variety of 
cultivated blueberry can best be propagated by one of the methods 
here described, others by another. The most novel of the methods 
devised, but the one easiest of operation, is that of tubering. This 
method involves the same principle as that employed in stumping, 
namely, the forcing of new shoots in such a manner that their basal 
portions are morphologically scaly rootstocks, with a strong rooting 
tendency. The directions for tubering as applied to the swamp blue- 
berry are as follows: 
1. Make stem cuttings from outdoor plants between midwinter and early- 
spring, before the buds have begun to make their spring growth, and preferably 
on a warm day when the twigs are not frozen. A still better plan is to make 
the cuttings in autumn after the leaves have fallen, and store them for about 
two months in moist sphagnum moss on ice at a temperature just above freezing. 
2. The cuttings are to be made from vigorous plants grown in w^ell-lighted 
situations and with stems therefore well stored with starch. Use unbranched 
portions of the old and hardened branches and stems, about a quarter of an 
inch to an inch, or even more, in diameter. From 3 to 4 inches is a suitable 
and convenient length. Make the cuts with pruning shears or a fine-toothed 
saw and remove the bruised wood at the cut ends with a sharp knife. Be 
careful not to injure the bark or split or strain the wood. 
3. Lay the cuttings horizontally in a shallow box or other cutting bed of pure 
clean sand and cover them to the depth of about half an inch. IMoisten the 
sand well with rain water, bog water, or other pure water (free from lime) 
from a sprinkling pot, and see that the sand is closely and firmly packed about 
the cuttings. Cover the box or cutting bed with a pane or panes of glass, the 
top of the box being flat, so that the glass fits it rather snugly. The box should be 
so prepared that any surplus water in the sand will drain away beneath through 
holes in the bottom covered with clean broken crocks and sphagnum moss. 
1 For a fuller discussion of the conditions under which leaves decompose into leaf peat 
as distinguished from leaf mold, and the fundamentally different effect of the two on the 
growth of plants, consult " The Formation of Leafmold," Smithsonian Report for 1913, 
pp. 333 to 343 (also separately printed). 
