PLUMS IN RELATION TO PRUNING 27 
The spurs branch and remain thrifty for many years but increase very little in 
length and produce small or irregular crops. Old spurs are rarely found on 
trees which have been regularly pruned to induce numerous fruiting twigs and 
are growing well. Much of the new growth at nodes of 1-year-old wood on trees 
of fruiting age is very short and may be classed as spurs. The number of 
these which grow to longer twigs is comparatively greater when the growth 
of the previous year is cut back. The section of the branch producing short 
lateral spurs is very prolific while the spurs are young. Many of these 
spurs are leafless and die after their fruit ripens. Those among these lateral 
spurs which bear fruit and live rarely fruit the following season ; but many of 
them grow to twigs. On the larger, more thrifty twigs much of the crop is 
borne on 1-year leafless spurs, but with the shorter, more slender twigs much of 
the 1-year-old wood bears fruit, and all but a small percentage of it is at leafless 
nodes (pi. 25, B). On the large, thrifty, cut-back branches which are given 
abundant light, new spurs sometimes grow to twigs while bearing fruit. 
It is on 1-year twigs and 1-year spurs that much of the crop is produced, as but 
few spurs live after fruiting ; or, if not fruiting, grow to twigs. The need for 
cutting back twigs or branches in pruning and providing conditions favorable 
for a thrifty twig growth is therefore apparent (pi. 25, C). 
Where twigs or spurs die or are broken off, new ones are seldom produced 
in their places. The vegetative vigor is largely centered in the ends of the 
branches and twigs, and a moderate thinning out or cutting back of branches 
is practiced in the annual pruning. 
IMPERIAL EPINEUSE 
Tree upright spreading, vigorous, branches freely, find retains spurs for many 
years. 
Spurs form at almost all nodes along the new shoots and larger twigs and 
along the terminal portion of the smaller twigs. They remain thrifty and pro- 
ductive even along the old framework branches if the tree has been kept open. 
They are rather long and often produce several branches which provide an 
abundance of fruiting surface. The spurs are very strong and are seldom 
broken from the branch. If they die or are broken off they are seldom replaced 
by new ones. In the hotter, nonirrigated sections spurs form at terminals of 
almost all twigs and branches, and the tree increases in size but little if the 
branches are not headed back (pi. 26, A). Under cultural conditions favorable 
for wood growth the spurs are longer than otherwise, especially if fruit crops 
are light, a branch of the spur often growing to a short twig and the fruiting 
branch becoming well set with fruiting twigs (pi. 28, B). 
New shoots or twigs may spring from spurs either young or old in any part 
of the tree that is given light if the tree is vigorous. When pruned, the new 
shoots usually grow from spurs immediately below where a branch was cut 
back, but they may start from spurs on any part of the cut-back branch or 
even from the main branch near where a branch was removed (pi. 26, C). 
The tendency is for the spur to maintain a more or less uniform vigor in all 
parts of the tree rather than in a restricted portion of it. This tendency is 
more pronounced with this than with most other varieties. The Sergeant is 
an exception. 
In the hot irrigated sections the new growth on unpruned trees is short and 
but few branches are produced to replace those removed in thinning. Here an 
open tree of strong branches may be maintained with but a minimum of 
pruning after the tree has been formed (pi. 26, A). In the cooler coastal regions 
the wood growth is more vigorous than in the hotter valleys, and the tree tops 
are inclined to become dense, making more thinning necessary to prevent 
excessive shading in the interior part of the tree. In irrigated orchards in 
cool sections, trees severely headed back each winter produce vigorous upright 
shoots at the top (pi. 26, D). Under this treatment twigs grow from one or 
more branches of almost all spurs throughout the tree, and heavy crops are 
borne both by the branches of the spur which did not grow to twigs and by 
spurs which developed on new twigs (pi. 26, E). 
The fruit is borne throughout the tree and almost entirely on spurs with 
leaves. On wood 1 and 2 years old the crop is light, but on spurs on wood 2 
years old or older it is more or less uniform throughout the tree. On 1-year-old 
wood any fruit produced is found mostly at nodes where spurs are forming. 
Some fruit is found along the leafless section near the base of the slender 
1-year-old twigs and on the larger 1-year-old shoots. Some spurs set fruit along 
