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JOURNAL OF ECONOMIC ENTOMOLOGY 
[Vol. 17 
orchards—in fact, I have yet to hear of any injury where the material 
was used in commercial peach orchards, even one year old orchards. 
I understand some injury resulted from the use of Paradichloro - 
benzene last fall in other sections of the country, rather extensive in¬ 
juries, but the conditions were entirely different from what we would 
ever expect to have in Indiana, and I do not believe that these experi¬ 
ments should deter us, in the central west, from following our present 
recommendations. 
Mr. W. E. Britton: I would like to inquire if this material is not 
covered ? 
Mr. S. C. Chandler: Yes, we cover it. 
Mr. W. E. Britton: It seems to me the chief diffiiculty would be in 
covering it where you do not remove the weeds. 
Mr. vS. C. Chandler: We have had no trouble of this kind. I 
picked out an orchard especially grassy and weedy, more than we 
expected to find in a commercial orchard, and we had no difficulty in 
handling the material. 
Mr. Alvah Peterson: In New Jersey, in treating about 250 nursery 
trees we killed 75 per cent of the trees w T ith one-fourth ounce per tree. 
On two year old trees in some orchards, we have found considerable in¬ 
jury. However, there are many growers in the state of New Jersey who 
are at the present time using one-fourth ounce per tree on trees one 
year old, and three-eighths to half an ounce on two year old trees. 
During 1923 we also saw injury in an 8 year old orchard, which we 
believe was due to paradichlorobenzene. This orchard was weakened at 
one time by frost injury, and it was also severely infested. The grower, 
for the first time, last fall (1922) treated that orchard with paradichloro¬ 
benzene, and 25 per cent of the trees w r ere dead at the first of September 
of this year (1923). 
Mr. F. H. Lathrop: I was wondering whether any one has done any 
w^ork with the actual concentration of the gas. Even if a two year old, or 
a one year old tree is given, say one-quarter of an ounce of the material, 
the actual concentration in the gas may be much greater than one ounce 
on a tree four to six inches in diameter, so we are really giving it a 
heavier dose of the material—that is, considering it on the basis of the 
concentration of the gas. I was wondering whether any work has been 
done along the line of determining the concentration of the gas that the 
trees can stand? 
Mr. S. C. Chandler : I do not think any work has been done along 
that line. 
