12 BULLETIN 1169, U. S. DEPARTMENT OF AGRICULTURE. 
must be placed around the trees when the soil temperature is 60° F. 
orhigher. Figure 1 shows that the soil does not warm up sufficiently 
for applications before April 1. On the other hand it is important 
to prevent tree damage from the borers as soon as possible and to 
kill them before they have gone deep in their galleries or have attained 
large size. Consequently, do not wait later than April 1 for spring 
applications. 
The results from the application made on December 6 were very 
poor. When the examinations on these trees were made on May 5 
every borer that could be located was active. Of course, some may 
have been killed and decomposed before the examinations were made. 
The poor results can be attributed to the fact that the soil is too cold 
during December in Georgia for the generation of gas from paradichlo- 
robenzene crystals. As shown in Figure 1, the average soil tem- 
perature during December, 1921, was 56° F. Some of the applica- 
tions made at two-week intervals after October 15 gave very good 
results, yet 25 per cent of the borers were active in the spring in trees 
that had been treated with paradichlorobenzene October 24, or two 
weeks later than the usual time. 
For best results, paradichlorobenzene must be applied in the early 
fall, at the close of the oviposition period of the adult. At this time 
the borers are small and the galleries are shallow. Furthermore, 
1-ounce doses applied immediately after the oviposition season will 
pene entirely in six weeks, or before the soil temperature becomes 
too low for the gas to generate. ‘The work reported here shows that 
the best results with paradichlorobenzene for peach-borer control in 
central Georgia will be obtained by placing the erystals around the 
trees October 10. 
CORRECT METHOD OF APPLYING PARADICHLOROBENZENE. 
In practically every case where a peach grower failed to get satis- 
factory control of the peach borer with paradichlorobenzene it was 
found that the directions for applying the chemical were not closely 
followed. It is absolutely essential to follow the directions very 
closely if best results are to be obtamed with paradichlorobenzene. 
It must be remembered that the gas given off from paradichloro- 
benzene crystals is much heavier than air, and borers in a tree above 
the point where the crystals are placed will not be affected by the 
gas. Consequently, the first thing to do in treating a tree is to deter- 
mine the topmost borer gallery. Usually this will not be above the 
soil level, and, in such case, the soil should not be mounded or dis- 
turbed before applying the paradichlorobenzene, except to remove 
weeds, stones, etc., and to make the soil surface level, using the back 
of a shovel. If gum, sawdust, or frass is thrown out from the tree 
trunk above the soil level, one can be reasonably sure that some 
borers are working in the tree above the soil. In these cases mound 
up the tree with earth, so that the ring of crystals can be placed above 
the topmost borer gallery. This is necessary in order that the gas 
may reach the borers above the soil level. Do not mound trees 
before applying the chemical, however, unless there are distinct indi- 
cations of borer work above ground. 
The dose of paradichlorobenzene is then applied in a continuous 
band about 2 inches wide and about 1 inch from the tree trunk. Care 
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