6 BULLETIN 1477, U. S. DEPARTMENT OF AGRICULTURE 
Trees of many varieties which produce a heavy new growth and form 
compact tops require thinning of branches to admit sufficient light for 
the thrifty growth of fruiting wood in the interior of the tree. With 
other varieties which are very open and make but a short new growth, 
it is preferable to cut back the larger new shoots rather than to 
remove them. This provides for the growth of new wood needed to 
maintain the desired vigor for the production of large fruit and to 
protect the larger branches against sunburn. Jefferson, California 
Blue, and Golden Drop are among those which grow more slowly. 
Civilian and Sergeant are representative of those that are also open 
but are more vigorous. The trees of these varieties soon become very 
spreading and open from lack of new branches, if pruning to encour- 
age branching and to maintain vegetative vigor is neglected. A few 
varieties are inclined to produce their new shoots by an outgrowth of 
the tips of branches rather than from spurs or the production of new 
branches. This tends to keep the tree open, and heading back to 
induce the growth of the desired number of branches is often neces- 
sary. Varieties in which this characteristic is prominent include the 
Sergeant, Clyman, California Blue, and Sugar. 
The health or thrift of the tree and the conditions under which it 
is growing, whether favorable or otherwise, are indicated by the 
new growth made during the current season, as is also the tendency 
toward fruit fulness. New shoots that make a strong growth may be 
headed back less severely than weak, slender ones and a larger crop 
of fruit of good size produced, provided good cultural conditions 
are maintained. If the tree is severely headed back each year, it is 
burdened with the production of a new crop of wood as well as with 
that of fruit. The danger of too little pruning lies in reducing the 
vegetative vigor of the tree to a point below that needed for the 
production of large fruit. If the season's wood growth is short it 
indicates drought, other unfavorable growing conditions, or insuffi- 
cient pruning; and small fruit may be expected if the trees are 
allowed to bear even moderately heavy crops. Also, a much smaller 
number of lateral twigs will be produced by the varieties which nor- 
mally produce spurs. Under the same conditions the trees which 
bear their fruit on twigs will come to production more promptly 
than those making a heavy growth. 
If the current year's shoots which develop near the point of head- 
ing back are comparatively short, stout, and rigid, it indicates that 
the tree will be more open, will produce fewer fruiting branches, and 
will bear its fruit on spurs or short spurlike twigs. If the new 
shoots are long and slender, as they are on the Beauty and Santa 
Rosa, a thrifty wood growth is needed to enable the tree to produce 
large-sized fruit, and the tree is inclined to become compact and re- 
spond quickly to either favorable or adverse growing conditions. 
These rapidly growing shoots often branch during their current 
season's growth. Several of these branches, which often grow to 
considerable length, sometimes appear on a single shoot and cause 
the tree top to become very compact and shade the lower portion. 
This branching indicates that the shoots on which they grow will 
not produce heavy crops as promptly as shorter, stouter,\mbranched 
ones. By removing the large shoots and the small, the slender, and 
the more frail ones, leaving the stoutest of those of medium length 
