Feb. 7, 1916 
Further Studies on Peanut Leaf spot 
893 
infecting. In case the former was employed, the peas were to be im¬ 
mersed for 15 minutes in a solution containing 1 pound of copper sulphate 
to 20 gallons of water; in case the latter was used, 1 pint of formaldehyde 
to 20 gallons of water, the peas to be steeped for an hour. Tests of the 
effectiveness of these seed treatments were made during the past season 
(1915) at Eutaw, Ala. One field, designated as field 10, had previously 
grown several successive crops of peanuts; the other, field 11, had not 
been cropped with peanuts at least during the four preceding years. Each 
field was divided into four plots. Plot 1 in each field was planted with 
unshelled peanuts which had been immersed in copper sulphate; those 
in plot 2 were not shelled and were immersed in formaldehyde; those in 
plot 3 were given no treatment; in plot 4 no fungicide was employed, 
and the peanuts were shelled prior to planting. The conditions in field 10, 
as noted in three successive examinations, are given in Table II. 
Table II .—Summary of results of leaf spot tests onfield 10 in IQ15 , infested with leaf spot 
Plot and treatment. 
Aug. 6. 
Aug. 14. 
Aug. 21. 
Plot 1. Peanuts, not shelled, steeped in copper sulphate: 
Total number of diseased leaves on 25 plants . 
882 
1 1 AQ2 
7 , 201 
Number of diseased leaves per plant— 
Maximum. 
79 
10 
7 S 5 
no 
Of 
Minimum... 
11 
I* 437 
* to 
Plot 2. Peanuts, not shelled, steeped in formaldehyde: 
Total number of diseased leaves on 25 plants. 
*0 
3 . 020 
Number of diseased leaves per plant— 
Maximum. 
63 
x 
*/ HO / 
I AA 
Of 
241 
Minimum .. 
e 
Plot 3. Peanuts, not shelled, no treatment: 
Total number of diseased leaves on 25 plants . 
1,022 
0 
2,028 
178 
12 
*y 
At 234 . 
Number of diseased leaves per plant— 
Maximum . 
94 
*rf 
207 
Minimum .. 
t 
30 
Plot 4. Peanuts, shelled, no treatment: 
Total number of diseased leaves on 25 plants . 
§ 
545 
45 
2 
1,184 
128 
oy 
2 « 740 
Number of diseased leaves per plant— 
Maximum . 
t*t y 
204 
Minimum . 
is 
26 
Infections were observed in this field as early as July 26 and were 
probably present at a much earlier date. Plot 3 will be seen to have 
had a larger number of diseased leaves on August 6, and during the two 
successive weeks, than did any of the other plots. It would naturally 
follow from this that s£ed disinfection is not without appreciable effect. 
It was felt, however, that it would be necessary to duplicate these results 
in several localities during several seasons before one could safely con¬ 
clude that seed treatment is of any practical value, especially in the light 
of the data to be subsequently presented. 
Field 11, which can be directly contrasted with field 10, really shows 
the result of seed treatment coupled with rotation. No tabulation for 
field 11, such as has been made for field 10, has been prepared, but the 
important facts in regard to this field are as follows: Eeafspot was not 
apparent until August 6,11 days after it was first seen in field 10. Only 
five plants in the whole field were found to be affected on this date, and 
