April, ’24] SNAPPt PARADICHLOROBENZENE AND PEACH BORER 253 
Mr. J. J. Davis: I would like to ask Mr. Peterson the season he got 
injury to nursery stock ? 
Mr. Alvah Peterson: We carried out experiments for two years. 
Some applications were put on in May, and other applications were put 
on in September, and we ran experiments all the way from four days up 
to indefinite exposures. 
Mr. S. C. Chandler: May I ask the type of soil? 
Mr. Alvah Peterson: This happened to be a heavy, Penn loam 
soil, and in another nursery it was a sandy loam soil. 
Vice-President S. B. Fracker: The next paper is by 0. I. Snapp. 
THREE YEARS OF PARADICHLOROBENZENE EXPERIMENTS 
IN THE SOUTH 
By Oliver I. Snapp, Entomologist, U. S. Bureau of Entomology, Fort Valley, Ga. 
Abstract 
Paradichlorobenzene treatment of peach trees for control of the peach borer, 
Aegeria exitiosa Say, has become an annual practice in the program of orchard manage¬ 
ment in Georgia. Five hundred thousand pounds of the material were used in the 
Southeast during the 1923 season. The results of experiments indicate that under 
normal conditions the large doses exposed for short periods are not as effective as 
the smaller doses exposed for four to six weeks. No tree injury resulted from the 
use of the various doses around three, four and five year old peach trees in Georgia 
during 1921 and 1922 when normal weather conditions prevailed. However, during 
the 1923 season a precipitation deficiency occurred accompanied by abnormally high 
temperatures. These unusual weather conditions caused rapid action from the gas, 
and as a result some rather severe injury has shown up on three year old trees from 
the use of the ^4 and one ounce dose. During each of the three years no injury has 
resulted from the use of the ounce dose around four and five year old trees for 
twenty eight days. One and two year old trees have shown, each year, more or less 
injury from the use of the yi and yi ounce dose. To date no injury has been re¬ 
vealed from allowing the mounds to remain around the trees over winter. Late 
October and November applications of paradichlorobenzene gave a control of around 
seventy-five per cent. December applications were worthless. Applications made 
around April 1st in Georgia gave about seventy per cent control. Laboratory ex¬ 
periments show that the gas is liberated at about the same rate in both sandy loam and 
clay soils. Tests in the laborator}^ have repeatedly shown that the higher the moisture 
content of the soil and the lower the temperature, the slower is the action of the gason 
the borer. 
The use of paradichlorobenzene in the South for control of the peach 
borer {Aegeria exitiosa Say) has rapidly increased in popularity during 
the last three years. A large percentage of the peach growers in Georgia 
have now adopted the treatment, and the use of the chemical in that 
state has become an annual practice in the program of orchard manage- 
