312 
Journal of Agricultural Research 
Vol. XXXI, No. 4 
been unused for 20 years prior to 1918. Potatoes planted in it that 
year developed wart, although the seed is said to have been clean. 
The source and distribution of the disease in this garden were there¬ 
fore unknown, but evidently infection was not general. No further 
test plantings were made. 
Table II .—Results of chemical treatments made in the fall of 1920 on plots planted 
to wart-susceptible potatoes in 1921 
Wart 
present at 
harvest 
(per cent) 
Application 
Plot « 
No. 
Chemical used 
Formula 
Rate per square 
foot 
0 
Alcohol___ 
70 per cent_ 
1 pint. 
14 
27 
Mercuric chloride+sodium chloride.__ 
Mercuric chloride+sodium chloride+ 
1 to4J4.. 
9H grams 
10 
93 to 100 
400 grains, 4 pounds to 
25 gallons. 
16-16-50 or 8-8-50_ 
1 pint.. _ 
7,8 
5,6,16 
3 
0 to 100 
water. 
Bordeaux_ 
do 
0 
Carbolic acid (crude) ___ 
gallon. _ _ 
47 to 48 
Chloride of lime____ 
50-50— _ .. 
ipint_ 
11,12 
22 
*>0 
Creosote___ _ 
yi gallon. ... 
0 
Kerosene____ 
lpint_ _ 
13,15 
1,2,19,21 
20 
0 
Lime-sulphur_ _ .. . 
1 to 3,1 to 6,1 to 12. __ 
..—do_ 
*0 
Potassium permanganate__ 
1 to 25.... 
_do_ _ 
b 0 
Sugar_T__ 
2 ounces_ 
24 
b 0 
Sulphur.._ ___ __ 
^nr or & pound— 
17,18,23 
4,9 
37 to 90 
Checks.____ 
a Plots were 5 by 10 feet. h Soil probably very lightly infected, if at all, in these plots. 
East 
2 
4 
6 
8 
10 
12 
14 
16 
18 
20 
22 
24 
1 
3 
5 
7 
9 
11 
13 
15 
17 
19 
21 
23 
West 
South 
Chemical Treatments in 1921 
PLOT EXPERIMENTS 
In the spring of 1921 four gardens with space for 100 plots, each 
5 by 10 feet, were secured at Sandy Run, near Freeland, Pa., for a 
more comprehensive test of chemical soil sterilization. Since the 
preliminary tests of chemical penetration indicated that heavy appli¬ 
cations were necessary to secure penetration, and since no dependence 
could be placed on rainfall in the spring, these treatments were 
S lanned for heavy applications of solution or for dry chemicals. 
lany of the treatments planned were so drastic as to make it almost 
certain that they would prevent the growth of crops for a time. It 
was hoped that an effective treatment could be found that would 
not prove injurious to crops, but wart extermination was necessarily 
the primary consideration. Since no effective chemical soil-steriliza¬ 
tion treatment for this disease was known, any successful treatment, 
however drastic or expensive, would be a considerable advance and. 
offer a basis for further study. 
Results in 1921, 1922, and 1923.—The details of the chemical 
soil treatments tested in 1921, including the strength, amount, form, 
and method of application, together with the results secured in wart 
control, are given in Table III. The diagram on Figure 3 shows the 
relationship of the plots to each other and shows the occurrence of 
wart in plots and checks in 1921 and 1922. 
