PLUMS IN RELATION TO PRUNING 17 
vigorous growth. The declining vigor of spurs is more pronounced in coastal 
sections where summer temperatures are low than in the warm interior 
valleys of California. 
Tree very vigorous, upright, inclined to branch freely but to make few 
framework and secondary branches and to produce numerous small branches 
and twigs. Spurs are produced in abundance and retained over long periods 
in parts of the tree which are kept open (see pi. 1, C). 
Large shoots which become framework branches grow from stubs of branches 
which have been headed back, and along older branches near the point where 
branches have been removed, but seldom from unpruned parts of the tree. Like 
the smaller branches and twigs, they terminate in spurs, although they resume 
their terminal growth under conditions favoring wood growth. They make 
a rapid long growth if the trees are irrigated and the tops headed back, and 
early in the summer they send out numerous lateral twigs which vary in 
growth from a few inches to a foot or two in length (pi. 8, A). 
The lateral fruiting twigs form on the current season's growth only, do not 
branch except to form fruiting spurs, remain slender and become drooping, 
increase in length when the season is favorable for wood growth, and their 
spurs are prolific over a period of years (pi. 8, B and C). Under poor growing 
conditions but few of these twigs develop, and they are short and slender. 
Vigorously growing trees with their heavy crop of fruiting twigs soon form 
dense tops which shade the fruiting spurs and branches below, and the fruiting 
wood in this part of the tree soon disappears. On small branches or on larger 
ones which are not headed back or are cut back to lateral branches only a few 
lateral twigs appear, but numerous vigorous spurs develop along all branches 
(pl. 8, D). 
The fruit spurs are short, stout, and compact and are not easily broken 
from the branch. They develop at almost all nodes on both slender twigs 
and the larger branches where twigs have not developed. In the densely shaded 
portion of the tree the 1-year-old spurs are often leafless and die after fruiting, 
but those which become well established are very persistent and remain for 
many years if given light. 
Fruit is borne, for the most part, on spurs with leaves and along twigs 
and larger branches extending well down on the old wood. Some fruit is 
found on 1-year twigs where spurs are forming and on leafless 1-year spurs 
along the lower portion of the larger 1-year shoots. 
With its slender unbranched fruiting twigs and short, compact, persistent 
spurs this variety closely resembles the Eldorado in fruiting habits, except 
that the Eldorado produces its lateral fruiting twigs on 1-year-old wood, 
whereas with the Duarte they appear very early on the current season's 
growth. These fruiting spurs and twigs also resemble those of the Santa 
Rosa and Beauty, but these varieties are decidedly more inclined to branch 
and to form numerous secondary branches and therefore to become more com- 
pact than the Duarte. 
Tree upright, open, and vigorous, inclined to branch but little after reaching 
full bearing, to make but little terminal growth if branches are not cut back, 
and to produce and retain fruit spurs along the entire length of the branches 
(pl. 9, A). 
The spurs branch only a little, but they add considerably to their length 
from year to year and reach a greater length than those of other varieties of 
the Japanese group. In this characteristic they resemble more the short-twig 
type of spur common in the domestica group than the rosette type most common 
in the Japanese group (pl. 9, B). They remain thrifty and productive for 
many years even along the old framework branches of the tree, but are often 
slender and are rather easily broken. If broken off they are seldom replaced 
by new ones. Few of the side branches of the spurs live more than a very 
few years, and many die after they bear one crop of fruit. This leaves fewer 
points of the spur for fruit production than is usual with other Japanese 
plums and makes fruit thinning easier and large sizes of fruit more probable. 
When the branches are headed back the spurs increase more in length than 
otherwise, but seldom grow to twigs or branches, as do those of most other Jap- 
27428°— 27 2 
