July i, 1918 
True Nature of Spinach-Blight 
53 
ferable from the Viroflay to the Savoy type, and vice versa, thus indi¬ 
cating that the same disease may develop in various sections where 
spinach is grown, regardless of the type of plants used. 
SOIL TRANSMISSION OF SPINACH-BLIGHT 
To determine whether spinach-blight is carried in the soil, blighted 
areas were selected in each of three fields on an adjoining farm. The 
blighted plants were removed from the areas in each field, and one flat 
was filled with soil from each area, care being exercised to take the soil 
from around and under where the blighted plants had developed. The 
three flats of soil were brought to the greenhouse and covered with cloth 
cages. A fourth flat of the same size was filled with steamed greenhouse 
soil to serve as a control. The following night the greenhouse was fumi¬ 
gated with tobacco to kill insects. Three days after bringing the flats 
to the greenhouse they were planted with four lots of spinach seed from 
different sources. The control flat was planted with similar seed. 
Previous to planting, the seed was soaked in 1 to 100 formaldehyde for a 
few minutes. The four lots of seed in each flat were separated from one 
another by thin board partitions. For a period of 75 days these flats 
were left in the greenhouse. No signs of blight developed in any of the 
plants. The plants in the flats of field soil were as healthy as those from 
the same seed grown in steamed soil. Therefore it would appear that 
spinach-blight is not carried in the soil. 
To insure that neither the transfer of soil from the field to the green¬ 
house nor the modified conditions of the greenhouse was responsible for 
the failure of blight to develop on the plants grown in the various lots of 
soil, this experiment in somewhat different form was duplicated in the 
field on an adjoining farm. A bed of spinach which had a number of 
blighted areas in it was used. Four areas were selected where uniform 
outbreaks of blight had developed. The blighted plants, including the 
roots, were removed from the soil, and all traces of vegetation which 
might harbor insects were removed from the first three areas selected. 
In the fourth area the blighted plants were left exactly as they grew in 
the field. A trench the size of a cage approximately 2 by 3 feet in area 
was dug, the cage set therein, and the soil weU banked about the outside 
in order to insure that no insects should enter from below. After the 
four cages had been placed, the soil within them was treated as follows: 
In cage 1 the soil was loosened and planted to two lots of spinach seed 
which had been disinfected in 1 to 100 formaldehyde for a few minutes 
before planting. Four days later, before the spinach plants were up, the 
soil in this cage was soaked with a 40 per cent nicotine-sulphate solution 
(1 to 100) in order to kill any insects. Cage 2 was planted with spinach seed 
which had been disinfected with 1 to 100 formaldehyde. The soil in this 
cage was left in the same condition as after it had grown blighted plants, no 
attempt being made to free it of insects. In cage 3 the soil was treated in 
