1 6 BULLETIN 70. 
rows joining the infected patch. Apparently the disease gradually 
spread from the infected soil. Most of the plants in this plot developed 
small tubers and some of them grew no tubers at all. From eight rows 
one hundred and forty pounds of rough, corky potatoes were gathered. 
In some cases the plant apparently failed to put out tuber stems, while 
in others, the stems which were put out had been injured or completely 
cut off, producing Little Potatoes, and a number of the plants produced 
Aerial Potatoes. On October 10th, it was impossible to find a plant in 
the plot which was not more or less affected with the disease. The 
root system was also abnormally developed. It too showed the effects 
of the disease. The younger roots and root tips suffered most. Many 
of them were dead, and a careful examination of the living and recently 
killed parts showed the presence of an abundance of Rhizoctonia hyphae. 
Plot II. was used for check. The seed of this plot was not treat¬ 
ed, and the plants were not sprayed. They came up nicely, but some of 
these blighted early and many of them were killed fully two weeks be¬ 
fore frost. It was found on examination, that many of these plants 
were more or less affected with Rhizoctonia. Nine rows yielded 1128 
pounds of tubers, which averaged 94 pounds per sack. 
Plot III. was planted with the roughest and poorest tubers of 
this lot of seed. They were treated with corrosive sublimate one day before 
planting but only about three-fourths of the tubers grew, and the plants 
were unusually slow in reaching the surface of the ground. This plot 
was sprayed four times. Diseased plants were less plentiful 
in this plot than in the preceeding. Seven rows produced 910 pounds of 
tubers, giving a gain of 4 per cent over check. These tubers averaged 
102 pounds per sack. 
Plot IV. The seed of this lot was treated with corrosive subli¬ 
mate one day before planting. The plants were fully five days later in 
reaching the surface of the ground than those of Plot II, but fourweeks 
later there was very little difference in the size of the plants between 
the two lots. These plants were sprayed four times which kept their 
foliage in an excellent condition, until injured by frost. Fifteen rows 
yielded 2,625 pounds of clean, smooth tubers, giving again of 40percent 
over check. It is quite evident that this gain would have been consid¬ 
erable more had the frost been a month later. The tubers averaged 106 
pounds per sack. 
For the sake of comparison, the methods of treatment 
and the yields of the different plots are given 
the following table. 
TABLE I. RESULTS IN TREATING SEED POTATOES. 
Plot. 
No. of Treatment 
No. times 
Yield per 
Gain over 
Average lbs 
per sack. 
rows. of seed. 
sprayed. 
row in ibs. 
plot No.2. 
No. 1 
8 None. 
4 
17* 
861 loss. 
No. 2 
9 None. 
None. 
125* 
94. 
No. 3 
7 Corrosive 
4 
130 
4 
102. 
sublimate. 
No. 4 
15 Corrosive 
sublimate. 
4 
175 
40 
106. 
The results of 
these experiments may 
be briefly 
explained as follows: The poor yield in experiment 
No. t, may be accounted for by the fact that the plot was 
situated by the side of a badly infected garden, where pota¬ 
toes had been grown for several years. It is probable that 
the disease spread through the soil from the infested patch. 
(The result of this experiment cannot be considered for 
this reason.) 
