ERADICATING THE COMMON BARBERRY 
39 
PARATOLUENESULPHOCHLORIDE 
When paratoluenesulphochloride (C 6 H 4 CH 3 S0 2 C1) was applied 
to the soil in 8-inch pots in which barberries were growing. 5.2 grams 
per pot failed to cause the death of the barberries, though a slight 
injury to a few leaves resulted. No field tests were made. 
ORTHOTOLUIDINE 
Orthotoluidine (C G H 4 CH 3 NH 2 ) is a light, oily liquid. It was 
quoted at 15 cents a pound in 2,000-pound lots. 
In greenhouse tests 2 cubic centimeters caused barberries growing 
in 8-inch pots to die after three days. This was the best showing 
made by any of the chemicals tried in the greenhouse. An applica- 
tion of 2 cubic centimeters to an 8-inch pot was considered the 
equivalent of 0.4 of a pint applied to a mid-sized bush in the field. 
However, in the field tests with this chemical the minimum dosage 
given a barberry was 1 pint. 
Table 15 gives the results of the field tests with orthotoluidine. 
Table 15. — Summary of treatments of individual, marked barberry bushes with 
orthotoluidine 
Date of 
treat- 
ment 
Date of 
final 
observa- 
tion 
1 
Quan- ! 
tity of 1 
chem- Method of application 
ical per; 
bush | 
Bushes cut 
off or 
left 
standing 
Location of area 
Bushes 
treated 
Bushes 
killed 
Per 
cent- 
: age 
killed 
1922 
Apr. 20 
Do.... 
Apr. 18 
Do.... 
May 20 
1923 
June 27 
—do 
—do 
—do 
July 3 
Pints | 
1 In circular trench of 
1-foot radius. 
1 In circular trench of 
2-foct radius. 
1 Drench 
1 j— "do"" — — — .— 
Standing.. 
-do 
Cut off- 
Standing. . 
...do 
Marshall, Wis. 
do 
do 
.....do 
Guinee, 111 
5 
5 
20 
20 
15 


1 
7 
5 


5 
35 
33 
Total . 
65 
13 
20 
1 " """(" " 
As was found to be the case with other chemicals tested, the most 
satisfactory method of application was as a drench immediately 
around the base of the shoots. Even with this method of applica- 
tion, however, the results were far from satisfactory. With sodium 
arsenite and sodium dichromate it was found necessary to use a fairly 
large volume of solution — that is, from 1 to 2 gallons per bush — to 
obtain uniformly successful treatments. Had it been possible to di- 
lute the orthotoluidine in some way without additional expense the 
results might have been more successful. Since the chemical is in- 
soluble in water, the cost of diluting it, no doubt, would have been 
considerable. 
The results with orthotoluidine also demonstrate the dangers of 
drawing too definite conclusions from the results of greenhouse tests 
with herbicides. This chemical was among the most effective in the 
greenhouse, whereas in the field it was very ineffective. On the other 
hand, kerosene did not appear at all satisfactory when tried on 
potted plants, but it is one of the two or three most satisfactory in 
the field. 
