PARADICHLOROBENZENE ON YOUNG PEACH TREES. rf 
ONE-YEAR-OLD TREES. 
Eight 1-year-old Hiley peach trees exposed 12 days with one-half 
and three-fourths ounce doses showed no injury to either the trees 
or trunks. Of four 1-year-old Hiley trees exposed 18 days to l-ounce 
doses two of the trunks showed some injury which might be attributed 
to the paradichlorobenzene. The trunk of one of these trees showed 
severe popper with small brown lesions in the outer bark layers 
at about the place where the crystal ring had been placed. The 
cambium was uninjured. The other injured tree showed only slight 
peppering of the outer bark layers with small brown lesions. Both 
of these trees appeared very healthy from the top, and had appar- 
ently not been affected by the paradichlorobenzene dose. 
TWO-YEAR-OLD TREES. 
Of thirty 2-year Hiley peach trees exposed to one-half and three- 
fourths ounce doses from three to six weeks, all appeared very healthy 
and vigorous from the top when the final examinations for tree in- 
jury were made. (PI.I.) The trunks also showed no injury what- 
ever, with the exception of four. These four showed a slightly pep- 
pered appearance in the outer bark layers, but the cambium was 
uninjured. Of sixty 2-year-old trees treated with doses varying 
from three-fourths to 2 ounces exposed to the gas from 4 to 12 days, 
all were very healthy and growing vigorously. The trunks of 58 
were uninjured, while 2 showed the outer bark layers slightly pep- 
pered with brown lesions. The 15 check or untreated trees were all 
healthy and vigorous when each examination was made. The trunks 
showed no abnormal condition of the outer bark layers or cambium. 
THREE-YEAR-OLD TREES. 
Sixty 3-year-old Hale peach trees treated with doses varying from 
one-half to 1 ounce showed no injury from the paradichlorobenzene 
to either the trunk or the tree at any of the three examinations. 
The mounds around 15 of these trees were not disturbed after the 
paradichlorobenzene was applied until the spring of 1922. The other 
45 trees were exposed to the gas for periods varying from three to 
six weeks. Forty-five other 3-year-old trees treated with 14 to 24 
ounce doses and exposed from 4 to 12 days showed no injury to the 
trunk or tree at any of the examinations. The 17 trees used as 
checks in this experiment appeared the same as the treated trees 
when each examination was made. The 83-year-old trees used for 
this experiment were exceedingly healthy and vigorous, and the bark 
layers were thick for trees of that age. 
FOUR-YEAR-OLD TREES. 
The trees used for the four-year experiment were of the Redbird 
variety, and the orchard as a whole was in very poor condition and 
the trees neglected. Sixty of these trees were treated with doses 
varying from one-half to 1 ounce and 45 were exposed to the gas for 
periods ranging from three to six weeks. The mounds around the 
remaining 15 were not disturbed until the spring of 1922. At the 
final examination 16 of the 60 trees showed peppering with brown 
lesions on the trunk at about the place where the paradichlorobenzene 
