' PLUMS IN RELATION TO PRUNING 23 
shoots. Also, an occasional twig appears on vigorous, unpruned trees in irri- 
gated orchards. The older part of the spur becomes stout and strong and 
is not easily broken from the trees, but the branches of the spur and its new 
terminal growth are readily broken. Many of the spurs which are broken off 
are replaced by new ones, more quickly than with almost any other variety. 
This indicates a strong vegetative vigor in the older wood (pi. 17, C). 
Leaves of this variety are of medium size, have short petioles, and often 
tend to curl. These qualities aid in keeping the tree open and in admitting 
light. 
Fruit is borne on spurs in all parts of the tree and also on nodes on 1-year- 
old wood (pi. 17, D and E). Fruits are seldom found on leafless spurs or at 
nodes of 1-year wood where spurs are not forming, except for a short 
section at the base of the 1-year-old wood. The vigor of spurs and twigs and 
the tendency to produce leaves and form spurs at barren nodes on 1-year-old 
wood are more pronounced than in almost any other variety. This variety is 
inclined to produce heavy crops, but only in alternate years. 
Tree vigorous, upright, open, and branches sparingly, except for spurs and 
twigs which appear along the entire length of the branch (pi. 18, A). With 
the little branching that occurs, an abundance of light is admitted to all parts 
of the tree. 
New shoots spring from near the point where branches are headed back or 
removed and from the terminals of shoots of the previous year and occa- 
sionally from spurs. They make a stout, erect growth, but are not numerous, 
and make a vigorous growth if the tree is growing in irrigated soil and the 
new wood is headed back each year. Under these conditions of growth new 
shoots grow almost entirely from the 1-year-old shoots which were headed 
back. This causes shade below and the loss of most spurs and twigs. On 
such trees there is a heavy set of spurs on the newer wood, and heavy crops 
are produced in the newer part of the tree (pi. 18, B). 
Spurs are retained for many years if the tree is kept open, and they con- 
tinue to be productive. They are of greater diameter than spurs of most 
varieties, but remain short, except that under good growing conditions an 
occasional one grows to a twig of several inches in length. The fruiting 
branches retain their vigor well, and a spur which has been broken off is often 
replaced by a new one, thereby maintaining a supply of fruiting wood. 
Fruit is borne on 1-year-old twigs and on spurs of all ages throughout the 
tree. On the 1-year twig the fruit is usually found at nodes where spurs are 
forming and uncommonly at leafless nodes. The inclination to form spurs along 
the more slender 1-year twigs and branches is more pronounced than with 
most varieties, and only a short section of the base of the branches is without 
spurs. Only a few fruits appear on the large 1-year-old branches, although 
numerous spurs which are retained for a long period form along them (pi. 
18, C). 
DIAMOND 
Tree vigorous and upright spreading, producing many large branches which 
divide freely into fruiting branches and twigs (pi. 19. A). New growth starts 
from almost all nodes of 1-year wood, both on small twigs and on large 
branches and even at nodes of slender 1-year-old twigs which are producing 
fruit, a characteristic more pronounced with this variety than with any other 
herein listed (pi. 19, B). On the short slender twigs this new growth consists 
largely in the development of fruit spurs, and along the larger 1-year-old 
branches it is of twigs or fruiting branches. All terminal buds, both of spurs 
and larger branches, are inclined to continue length growth instead of remain- 
ing as short spurs or twigs; and where conditions are favorable for wood 
growth the trees soon become compact if not kept open by pruning. Trees not 
irrigated or those pruned lightly, if at all, produce relatively more fruit spurs, 
the slender twigs throughout the tree being well set with them. Fruits on 
such trees are small if crops are regular ; therefore thorough thinning out of 
branches, accompanied in dry places by heading back, is needed to insure the 
growth of large-sized fruit (pi. 19, C). 
The fruit spurs which do not grow to twigs remain slender, seldom branching, 
and are inclined to be short lived. Few of those which do not grow to twigs 
