PLUMS IN KELATION TO PRUNING 21 
WICKSON 
Tree thrifty, upright, forms many fruiting branches, and is among the 
varieties most inclined to produce spurs (pi. 14, A). 
Following heading back, new shoots spring from near the points of pruning 
and along the main branches if the tree is open, and then mostly near points 
where, branches have at some time been removed. New twigs appear as an 
outgrowth of spurs or from a terminal bud of a twig but uncommonly from 
lateral buds on 1-year-old wood. The new shoots are not so long as those of 
most other varieties, but they are stout and, because of their short internodes, 
are heavily leaved. Although the new shoots are somewhat shoiter on trees 
of the Wickson than on those of other Japanese varieties, the spurs on the 1- 
year-old shoots are usually more vigorous. 
Spurs form at almost all nodes of 1-year-old wood on large shoots as well 
as on small twigs, although short twigs instead of spurs are occasionally 
produced at the nodes of both large and small shoots. The twigs are usually 
slender but produce many spurs and are very prolific (pi. 14, B). The spurs 
live for many years if the tree is growing well and has been kept open, but 
if the top is compact those in the interior of the tree are soon eliminated by 
shade. Where the trees are not vigorous, annual wood growth is short, necessi- 
tating severe cutting back to induce the growth of twigs. The new twigs grow 
from the terminals of young spurs or from the nodes of the short section of 
the 1-year-old wood which remain after pruning. This leaves but few spurs 
of wood more than a few years old. The twigs and spurs on such twigs are 
slender and brittle and easily broken during the fruit harvest. Many of them 
must be removed to permit the fruit on the remaining ones to grow to good 
size. Such trees produce their fruit on wood of but a few years of age, as 
the remainder of the branches are barren (pi. 14, C). 
Where little or no pruning is done, spurs form at terminals of twigs and 
larger branches, and these as well as lateral spurs remain for many years. On 
such trees there is but little growth of twigs or new shoots (pi. 15, A). 
In the cool coastal regions the spurs on trees which have been annually 
headed back and which are growing in deep, irrigated soil have remained well 
down in the center of the tree, but the growth of shoots is much shorter than 
on trees in the warmer sections. Tops that have been headed back appear to 
have gradually lost their vigor, and new shoots which appear are often 
produced along the old framework branches. 
Fruit of this variety is borne on spurs, on 1-year-old twigs, and to some 
extent on the shorter 1-year shoots growing on branches which have been 
headed back. On trees which are making a poor growth the crop is heaviest 
on 1-year-old twigs and on spurs 1 to 3 years old. Most fruit is found on 
spurs with leaves or at nodes of 1-year-old twigs where spurs are forming, 
although toward the base of the slender twigs most fruits are at leafless 
nodes. The leafless section at the base of larger shoots is shorter with this 
variety than with most others. 
Cutting back to induce a moderate growth of strong branches while the 
tree is young, thinning to admit light, and later shortening twigs and branches 
sufficiently to maintain vigorous spurs and considerable twig growth from 
spurs would appear to be the most desirable method of pruning for this 
variety (pi. 15, B). 
VARIETIES OF THE PRUNUS DOMESTICA GROUP 
AGEN (FEENCH PRUNE OR PETITE PRUNE) 
Tree round topped, spreading, vigorous, branches freely, makes numerous 
fruiting branches and twigs throughout the tree, and is inclined to continue 
terminal growth of all branches, twigs, and spurs (pi. 16, A). The small 
branches and twigs often remain slender, and if shaded or crowded they become 
drooping. The twigs and spurs are persistent. When well established, they 
remain thrifty for many years and by branching and increasing in length 
gradually form a compact tree. 
Though inclined to form twigs rather than spurs, when bearing excessive 
crops or under cultural conditions unfavorable to wood growth, spurs form on 
terminals of branches and twigs and in place of twigs along branches. In 
this case the internodes of branches and twigs are short, and concentrated 
