28 BULLETIN" 1477, U. S. DEPARTMENT OF AGRICULTURE 
the lower portion of the more slender 2-year-old twigs, but these fail to pro- 
duce leaves. This is more often true in the interior of compact trees where the 
spurs die after harvest. 
ITALIAN PRUNE 
Tree round topped, moderately vigorous, rather open, inclined to make but 
few framework branches, but to produce many small fruiting branches and 
twigs. 
The Italian Prune is probably more inclined to produce twigs instead of 
spurs than any other variety commercially cultivated in the Pacific States, 
fruiting twigs being produced at almost all nodes of the larger and more 
vigorous shoots (pi. 27, A). On these twigs and on small branches the fruiting 
twigs make but little growth during the first season, often resembling spurs-, but 
they grow to longer twigs the following year or die after producing fruit. The 
fruiting branches, although vigorous and long lived and inclined to send out 
numerous twigs, make but little diameter or length growth ; and after a few 
years without thinning out, their twigs increase in length from year to year, 
forming brushes of fruiting wood which droop badly (pi. 27, B). The smaller 
branches remain slender and bend readily with a load of fruit, and if they 
retain their bending position, sunburning of the main branch often results 
(pi. 27, C). The twigs are sensitive to shade, and with the accumulation of 
outer branches much fruiting wood through the interior of the tree disappears 
(pi. 28, A). 
Vigorous new shoots spring from near the end of large new branches which 
have been headed back and from headed-back old branches, although only slight 
shortening of old branches induces but little new growth except a moderate 
lengthening of the fruiting twigs near the end of the branch. By heading back 
the young trees or thinning the branches in older ones, large, erect, new shoots 
are readily produced. Shoots which form the large branches increase in length 
but little after they are a few years old, unless they are headed back to induce 
the growth of new shoots. In this they contrast with shoots of California 
Blue. Sergeant, and some other varieties. Where growing conditions are 
unfavorable and the outer part of the tree becomes dense, the secondary 
branches remain slender and become drooping, and injury by sunburning is 
common. Under good growing conditions large, erect shoots which may appear 
send out many short lateral fruiting branches, which gradually increase in 
length and rebranch, thereby providing much fruiting wood. 
Fruit is borne almost entirely on leafless nodes on 1-year-old twigs (pi. 27, A). 
Along 1-year-old branches which are below normal in vigor, twigs usually fail 
to make more than a short spurlike growth. Such twigs often bear no leaves 
or only small leaflets and die after the fruit ripens, if they bear fruit. On the 
vigorous branches such spurlike twigs occasionally bear fruit and continue 
growth to longer twigs ; but as this is not common, the yearly extension of the 
older twigs is needed to supply the fruiting wood. 
Pruning to thin out and reduce the number of twigs sufficient to induce a 
vigorous growth of twigs on the remaining branches and removing or heading 
back some large branches to induce the replacement of old fruiting branches 
with vigorous new ones should result in the vigor required for good fruit 
production (pi. 28, B). 
Observations on this variety have been confined very largely to orchards 
in the Pacific Northwest, where it is the principal commercial variety. 
JEFFERSON 
Tree only moderately vigorous, upright spreading, very open, makes few 
fruiting branches, and produces spurs instead of twigs. Most of the new 
growth appears on spurs and at terminals of branches. This variety is very 
prolific and inclined to be regular in bearing, and when in full bearing little 
wood growth is made. It is adapted only to soils which are deep and fertile 
(pi. 29, A). 
Large new shoots spring from the stubs of branches which have been headed 
back, near where branches have been removed, and also from the terminals 
of spurs and branches in any part of the tree. The Jefferson produces fewer 
large shoots, however, than most other varieties. If the new growth is regu- 
