ao BULLETIN 120, U. S. DEPARTMENT OF AGRICULTURE. 
PRUNING. 
The subject of pruning demands consideration because of its 
bearing on the problem of mildew control. 
Attention has been called to the abundance of mildewed tips that 
can be seen during the dormant period. From the infested buds on 
these tips large numbers of seriously diseased shoots develop the fol- 
lowing spring, and the question of eliminating them is a very im- 
portant one, because on them are produced the enormous numbers 
of spores which serve to infect the healthy foliage as soon as it 
appears. Pruning offers the only practical solution of this prob- 
lem, because, as has been stated, summer spraying is not effective in 
cases in which the entire twig and its leaves have become badly mil- 
dewed. The reason is that it is impossible to wet the entire mildew 
covering thoroughly, the spray collecting in drops, even when the 
operator is successful in wetting all parts of the shoot and its leaves. 
Particular attention should therefore be given to cutting out the mil- 
dewed tips, and that work should be made a part of the regular 
dormant-pruning operations. 
It has been stated that trees that are growing vigorously and pro- 
ducing large, thrifty leaves are less seriously affected by mildew than 
poorly growing ones, even though they are of the same variety. One 
of the commonly recognized effects of winter pruning fruit trees 
is the improvement in growth and foliage conditions that result the 
following year. The apple is not an exception in this respect, and 
the improvement in vigor that can thus be obtained by pruning 
should be taken advantage of in combating the mildew. 
To obtain the full benefits of winter pruning in the Pajaro Valley 
greater attention should be given to thinning out the trees. This 
should not be done by cutting out large framework limbs, but by 
pruning out far more brush than is ordinarily removed. Interlacing 
branches should be removed, and the current year’s growth should be 
cut back one-third to one-half, or even more in the case of very young 
trees or very vigorously growing shoots. There is a tendency to 
allow the lower branches to become so long that they droop almost 
to the ground. It is true, as usually claimed, that the best fruit is 
borne on these lower branches, but that condition has been brought 
about largely by the fact that the tops of the trees have become badly 
affected by mildew or have lost their vigor through other causes. 
For these reasons it is important that the tops of the trees should be 
cut back as well as thinned out, so as to increase their vigor. The 
long spindling branches in the lower parts of the trees should be 
gradually shortened and the vigorous young twigs should be cut back 
so as to induce fruiting. 
