PLUMS IN" RELATION TO PRUNING 31 
Vigorous shoots grow from branches which have been headed back and oc- 
casionally in well-open trees from points near where other branches have 
been removed, but seldom from unpruned parts of the branch. With trees 
which have had the new growth severely headed back each year the tendency 
is to make ITut little twig or branch growth along the older portion of the 
branches, and the new branches here are usually frail. The large new shoots, 
as well as smaller branches and twigs, soon terminate in spurs if not headed 
back to promote wood growth; 
Large, thrifty spurs form at almost all nodes of medium and large-sized 
1-year-old shoots except at the section near the base, although little fruit is 
borne on the 1-year-old shoots. On medium and small-sized 1-year shoots, 
considerable fruit is borne at leafless nodes near the base of the shoot, with 
the section beyond producing spurs. Where the new growth is short one-half 
or more of its length produces no leaves after the first summer ; and in un- 
irrigated sections where almost all new growth on bearing trees is short, head- 
ing back, sometimes into older wood, is necessary to induce a vigorous new 
growth (pi. 31, D). On slender twigs all nodes except those near the tip re- 
main leafless, although fruit is borne at some of them (pi. 32, A). 
Along the lower, heavier portion of the vigorously growing shoots, occa- 
sional twigs or spurs are produced during the first season (pi. 32, B). These 
grow at right angles to the branch and sometimes reach from a few inches to 
a foot or more in length, are stout, and bear well when 1 year old. Fruit is 
borne at leafless nodes, leaving the twig barren thereafter, with the excep- 
tion of a few spurs near the end. This type of fruiting wood is seldom found 
and on only a few varieties. The number and length of these twigs depend 
upon the vigor of the new shoot, which is seldom sufficient to cause their 
growth unless the tree was heavily cut back the previous winter. Slender 
spurlike twigs, which grow at right angles to the new shoots, appear also when 
the growth of the new wood is checked during the summer ; and, in this case, 
they appear upon small as well as large new shoots and are usually well out 
toward the end of the new shoot. The long spurlike twigs, like the shorter 
spurs, do not increase in length after the first season, but both remain vigorous 
and productive over a period of years (pi. 32, C). 
When the new shoots make an exceptionally rampant growth, such as some- 
times occurs on trees heavily headed back or recently top-worked, numerous 
long slender twigs instead of short spurlike twigs or spurs appear on the new 
shoots early in the season. These twigs bear fruit heavily when 1 year of age 
but are usually frail and die at the end of their second summer or produce 
only a few short spurs near the end. 
The fruit spurs grow to considerable length during the first season, increase 
in length but little thereafter, are large in diameter, rather easily broken, 
and quickly injured by shade. Those along older branches lose vigor if the 
new growth is regularly and heavily headed back, causing a heavy top growth, 
and those which die or are broken off are seldom replaced. The older branches 
therefore become more barren from year to year if care is not taken to prevent 
the breaking of spurs and to retain their vigor by maintaining an open tree. 
The spurs branch freely, becoming more spreading than those of most varieties 
of Japanese plums, but they remain more compact than the spurs of most 
varieties of the domestica group. 
Where there is no irrigation or where other conditions are unfavorable to 
wood growth, the new wood is short and slender, and large portions of the 
new branches fail to produce leaves except near the end. If spurs are pro- 
duced they will bear heavily at 1 year of age, and all except those near the 
end will die after the fruit harvest. Where such a twig or branch is cut 
back, removing the section of leaves, the remaining part will die back to the 
main branch after the fruit ripens. In this way the young spurs, side branches, 
and all twigs along the older branches soon disappear on trees which grow 
poorly. 
Because the tree is inclined to produce new shoots near the point of heading 
back only and to produce vigorous long-lived spurs on the remaining portion 
of the 1-year-old wood (if it was this which was mit back) and along all 
vigorous shoots which were not pruned, heading back should be practiced to 
encourage branching while the tree is young. Subsequently, sufficient thinning 
out and heading back should be done to keep the tree open for the admission 
of light to the fruit spurs and to induce sufficient new growth to maintain a 
strong vegetative vigor. In unirrigated sections the new growth of the shoots 
