24 
Bulletin 91 . 
reached the surface of the ground about the same time as those of the check 
plat. They all suffered some from this disease, and the crop was of a poor 
quality and many of the tubers were covered with sclerotia. Six hundred 
pounds of seed gave a return of 7,555 pounds of tubers for every pound of 
seed planted, a loss of about 8%. 
Results. —1. Diseased seed treated with the standard corrosive sub¬ 
limate solution and planted on old potato ground gave a loss of 20%. 
2. Seed free from the sclerotia stage, but more or less covered with 
the rhizoctonia stage, planted on old ground, gave a loss of 8%. 
TABLE HI., SHOWING RESULTS OF EXPERIMENT NO. III. 
Plat Number 
TREATMENT 
Number Pounds 
of Seed Planted 
Pounds of Pota¬ 
toes Harvested 
Yield in Pounds 
for every 
Pound of Seed 
Planted 
Per Cent, of Loss 
Number cf 
Rows to the 
Acre 
Check ____ 
600 
8270 
13.75 
5 
Treated _ 
600 
6515 
10.9 
20 % 
5 
Selected Seed_ 
600 
7555 
12.59 
Oo 
5 
Experiment IV —The following experiments were made by S. A. Brad- 
field in 1902 to test the value of treating diseased seed with corrosive sub¬ 
limate when such seed is planted on old potato ground. A short rotation of 
wheat, alfalfa and potatoes has been practiced on this place for a number 
of years. A fair crop of alfalfa was plowed under in the spring before 
planting. The soil in this field is of a black loam, slightly sandy; it slopes 
gradually to the south and east. The runs between the rows were from 
seven to eight inches deep, which made it possible by carefully watering to 
supply the roots with plenty of moisture, and at the same time to prevent 
the soil in which the tubers developed from becoming too wet and soggy. 
Second year’s Divide Pearl seed was used in these experiments. 
Plat I Check —This plat was located on lower and in slightly better soil 
than the other two experiments. All the tubers were more or less covered 
with sclerotia of Corticium. The seed was planted about May 18th. Five 
hundred and six pounds of seed yielded 11,553 pounds of tubers, giving a re¬ 
turn of 23 pounds of tubers for every pound of seed planted. These tubers 
were smaller, and were more or less covered with sclerotia. Careful obser¬ 
vation also showed that this lot also contained the most scabby tubers. 
Plat II —The seed of this plat was more or less covered with sclerotia, 
but they were treated with a solution of one ounce of corrosive sublimate 
to eight gallons of water for 1% hours nine days before they were planted. 
These plants were five days late in reaching the surface of the ground. A 
careful examination of plants from various parts of this plat showed plainly 
that most of the plants had their subterranean parts covered with the hy- 
phae of this fungus. Six hundred pounds of seed gave a return of 11,161 
pounds of tubers, making 18% pounds of potatoes for every pound of seed 
planted, but the tubers were cleaner, larger and better in every way than 
those in the Check plat. 
Plat III —This seed was taken from the same lot of tubers as those in 
the other experiments. All tubers having sclerotia on them were rejected, 
but many of the tubers were scabby and all of them were more or less cov¬ 
ered with the hyphae. This experiment occupied the highest and probably 
the poorest ground. Five hundred and four pounds of seed gave a return 
of 10,574 pounds, making 21 pounds of tubers for every pound of seed planted. 
A loss of 9%. However, the tubers were larger and cleaner than those of 
the Check plat. 
