22 MISC. PUBLICATION 657, U. S. DEPT. OF AGRICULTURE 
those showing indication of borer attack in the branches can often be 
saved by adequate watering and by applying a fertilizer such as nitrate 
of soda or stable manure. This treatment, ‘together with severe prun- 
ing of infested parts and adequate cultivation, will often result in 
marked improvement. An excellent way of providing better absorp- 
tion of water by the soil and at the same time of applying commercial 
fertilizer is to make holes in the soil by driving a crowbar or pickax 
10 to 12 inches deep at intervals of a foot or less. The treatment 
should extend as far out as the spread of the branches, each hole should 
be filled with fertilizer, and the soil about the tree should be frequently 
watered if rainfall is lacking. 
WATERING 
The effect of drought on trees and its bearing on insect attack has 
been mentioned frequently on previous pages. Experience has shown 
that lack of moisture is one of the most important predisposing factors 
inducing attack by insects, particularly borers and bark beetles. Con- 
sequently, adequate watering of the trees during dry periods will offset 
this threatened injury. 
Experimental work with some of the wood borers and bark beetles 
has indicated that, if done in time, watering is one of the most effective 
methods of preventing attack. Thorough - watering should be started 
just as soon as there is a deficiency of 1 inch or more e of rainfall during 
the growing season. On hard, poor soils, or in places where the soil 
around the tree is subject to a great deal of tramping or packing, it is 
well to water frequently during summer and fall. 
CARE OF TREES ON CAMP GROUNDS 
The use of groves for camp grounds, parks, or other purposes where 
people congregate presents a difficult problem in keeping these trees 
in good condition. In such locations the soil litter providing humus is 
usually raked off each year, and frequent tramping of the ground packs 
the soil, interfering with aeration and drainage, and even exposes 
some of the roots. It is practically impossible to keep the trees in 
healthy condition, and they frequently succumb to the attacks of bark 
beetles and other borers. Where the damage becomes very noticeable 
and severe, the only remedy seems to be to avoid the use of the area 
for several years and apply humus or fertilizer to improve the soil 
and increase the vigor of the trees. In recreational areas and public 
parks, it is advisable to plan the campgrounds or other areas fre- 
quented by large numbers of people so that different sites can be used 
alternately every few years. 
MECHANICAL BARRIERS 
Mechanical barriers for preventing the access of insects to portions 
of the trees on which they would feed are often very successful in pre- 
venting damage, particularly to roadside or other ornamental trees. 
Transplanted hardwood stock is frequently attacked by secondary 
wood borers that mine beneath the bark, girdling the stems of the trees 
before the plants become firmly est: ablished. W rapping the trunks 
with heavy paper, wire gauze, burlap, or other material that will pre- 
vent oviposition has been very helpful in protecting the trees the first 
year or two, or until they are well established. 
