. teat 
PARADICHLOROBENZENE ON YOUNG PEACH TREES, 13 
should be used to distribute the crystals as evenly as possible, as the 
action of the gas islocal. Use only pure paradichlorobenzene having 
a fineness of granulated sugar. One-ounce doses should be used on 
trees 5 years old and older, and if this material is used on younger 
trees the three-fourths ounce dose is suggested. After the crystals 
are placed around the tree, cover them withseveral shovelfuls of soil and 
compact with a sharp blow or two, using the back of the shovel. 
This produces a slight mound which prevents the crystals from 
washing and also serves as a container for the gas. Avoid pushing 
the crystals against the tree trunk with the first shovelful of soil. 
If paradichlorobenzene is used on trees younger than 5 years old, the 
mounds should be opened four weeks later to remove any unspent 
crystals or to allow any remaining gas to escape. In the latitude of 
central Georgia it will not be necessary to open the mounds after 
treating trees 5 years old or older. Plates II and III show proper 
and improper methods of applying paradichlorobenzene. 
For best results the chemical must be applied in the peach belt of 
central Georgia from October 10 to 15. e northern Georgia the 
material should be applied about October 1, and in southern Georgia, 
October 15 to 20. The same dates should be applicable for similar 
latitudes in the other Gulf States. 
LABORATORY EXPERIMENTS. 
In connection with the field work on paradichlorobenzene, several 
tests were made with the material in the laboratory. Field conditions 
were somewhat different from those in the laboratory, but the two 
were made as nearly similar as possible. ‘The evaporation of the gas 
in the laboratory was slower than in the field, as in the latter case the 
material was subjected to a higher temperature due to its being 
exposed to the direct rays of the sun. In testing the killing effect of 
paradichlorobenzene on peach-borer larve, the gas was concen- 
trated in a small area and the action was somewhat faster than under 
normal field conditions. 
RATE OF EVAPORATION OF PARADICHLOROBENZENE CRYSTALS. 
The paradichlorobenzene crystals used to determine the rate of 
evaporation were about as fine as granulated sugar. The soils used 
were red clay and sandy loam. One-half ounce of paradichloroben- 
zene was used in all tests and was imbedded from 4 to 6 inches in the 
soil, with the exception of one test, where the crystals were placed 
on the surface of the soil. Some of the soils were used just as they 
came from the field; others had various amounts of water added up 
to the point of saturation. 
In the sandy loam soils the crystals evaporated at about the same 
rate, whether 4 or 6 inches below the surface. The evaporation was 
somewhat faster in red clay when the crystals were only 4 inches 
down in the soil. The evaporation in the cages to which water had 
been added was retarded at first, but in about two weeks it was about 
the same as in normal” soils. It took from 91 to 135 days for all of 
the paradichlorobenzene to disappear, with the exception of the 
single cage in which the material was placed on the surface. The 
2 The soil used as it came from the orchard without the addition of water is henceforth designated in this 
paper as normal soil 
