16 
BULLETIN 796, U. S. DEPARTMENT OF AGRICULTURE. 
TWO-YEAR OECHAED TREES. 
The effect upon two-year orchard trees proved less serious, al- 
though much too great to make their fumigation practicable. On 
August 18, 1916, 20 Belle of Georgia trees were treated in an orchard 
at Vienna, Va. These trees were in their second season from plant- 
ing and were consequently two years older than the nursery trees. 
The soil was exceptionally stiff clay loam. With one or two excep- 
tions these trees were vigorous and normal. Table V gives the date 
of application, dosage, and the results of later observations on the 
effects of the fumigation. 
Table V. — Effect of stated doses of para-dicliloro'benzene on 2-year-old Belle of 
Georgia peach trees, Vienna, Va., 1916-17. 
Tree 
Nos. 
Condition 
of trees 
before 
treat- 
ment. 
Dose. 
Date of 
applica- 
tion. 
Condition of trees on specified dates of examination. 
Mar. 14, 1917. 
July 24, 1917. 
1 
2 
1 
Normal.. 
...do 
...do 
Weak... 
Jounce... 
...do 
£ ounce. . 
...do 
1916. 
Aug. 18 
...do 
...do 
Moderateinjury, notserious 
Slight injury, not serious 
do 
Fully recovered, normal growth. 
Do. 
Do. 
2 
...do 
Dead 
1 
2 
...do 
Normal.. 
...do 
Weak. . . 
Normal.. 
...do 
...do 
...do 
...do 
...do 
...do 
...do 
...do 
...do 
...do 
...do 
f ounce. . 
...do 
1 ounce. . 
...do 
2 ounces . 
...do 
3 ounces. 
...do 
4 ounces.. 
...do 
5 ounces.. 
...do 
6 ounces.. 
...do 
8 ounces.. 
10 ounces. 
...do 
...do 
...do 
...do 
...do 
Slight injury, not serious 
Severe injury, girdled 
Do. 
Dead. 
1 
2 
1 
Severe injury, three-quarters 
girdled. 
Slight injury, not serious 
do 
Partly recovered, normal 
growth. 
Fully recovered, normal growth. 
2 
...do 
...do 
...do 
do 
...do 
...do 
...do 
...do 
...do 
...do 
...do 
Severe injur y , girdled 
Dead. 
1 
2 
1 
Slight injury, not serious 
Severe injury, three-quarters 
girdled. 
Severe injury, girdled 
Fully recovered, normal growth. 
Partly recovered, normal 
growth. 
Dead. 
2 
1 
Traces injury, not serious 
Fully recovered, normal growth. 
Partly recovered, normal 
growth. 
Fully recovered, normal growth. 
Subnormal, stunted. 
Fully recovered, normal growth. 
Do. 
Subnormal, stunted. 
2 
1 
2 
1 
1 
Traces injury, not serious 
Slight injury, not serious 
Traces injury , not serious 
Moderate injury, not serious 
It will be noted by reference to Table Y that for all doses up to 
and including 5 ounces the injury to one tree is recorded as " slight " 
or less, while the other was injured more severely. Table Y also 
shows that on July 24, 1917, when they were again examined, all in- 
jured slightly had recovered and made a normal growth. For each 
dose, therefore, up to and including 5 ounces, one tree entirely re- 
covered and made a normal growth the season following fumigation. 
Apparently for the period over which the experiment was allowed 
to run, the smaller doses were sufficient to furnish a vapor of maxi- 
mum toxicity. Had the experiment been allowed to run longer, it 
is probable that a greater graduation in the toxicity of the various 
doses would have been observed, as the larger doses had by no means 
completely volatilized at the time the examination was made. As in 
