Wart Disease of the Potato. M.C. Potter. 247 
WART DISEASE OF THE POTATO. 
PRELIMINARY EXPERIMENTS. 
By MC. Poper, Sci, MA IOL.S. 
For some time it has been recognised that certain plants are 
associated with acid and others with alkaline soils, and that soil 
acidity or alkalinity is a determining factor in the distribution 
of plants. Atkins has recently correlated the range of hydrogen 
ion concentration with the growth of over one hundred plants. 
In a similar manner it is found that micro-organisms are also 
sensitive to culture media. Potts showed in 1905 that the 
turnip disease known as Finger-and-Toe was absent from slightly 
alkaline soils; Jamieson and later Atkins have also noted that 
this disease is more prevalent in acid soils. 
A series of experiments have been instituted in the Botanical 
Department of Armstrong College to determine the limits of 
hydrogen-ion concentration between which the potato can live 
and also to determine the fH range of Synchytrium endobioticum, 
the causal organism of wart disease. 
The experiment consisted in growing a non-immune variety 
of potato in soils of varying #H concentration, and ordinary 
garden soil taken from an old allotment was employed for the 
purpose. In the previous year this soil had been infected with 
wart disease and a crop of badly infected potatoes grown upon it. 
It was therefore a soil in which wart disease would occur and 
was in every way suitable for the experiment. 
The variations of soil alkalinity were brought about by the 
applications of different amounts of washing soda crystals and 
of chalk. 
Large ten-inch flower pots filled with the treated soil were sunk 
in the ground out of doors and a seed potato was planted in each. 
Controls. Two controls were taken; one of the original soil 
and the other of this soil specially mixed with wart diseased 
potatoes. The potatoes planted in both these pots gave rise to 
tubers infected with wart disease. 
Washing soda. Six pots were used and to the soil in these 
pots was added respectively 14, 28, 56, 112, 168 and 244 grams 
of washing soda. The soda was dissolved in water and poured 
over the surface of the soil. Any water running through was 
caught in a porcelain pneumatic trough and poured over the 
surface again, this operation being repeated until the water was 
all absorbed by the soil. The soil from each pot was then sepa- 
rately turned out, thoroughly mixed, and replaced. The fH 
of the soil in these six pots was found to be approximately 
8, 9, 9°5, 10, 10°5 and 11, the soil as taken from the garden 
being approximately 7:5. 
