Porato SPRAYING IN MINNESOTA 23 
MATERIALS TESTED 
The stomach poisons tested were: 
1. Lead arsenate. 
2. Zinc arsenite. 
3. Calcium arsenate. 
4. Paris green. 
Each of these poisons was applied with and without bordeaux 
mixture. 
The contact insecticides used were: 
1. Nicofume. 
2. Black leaf 40. 
3. Nicofume oleate. 
These materials were all applied with a four row traction sprayer 
equipped with a “bordeaux” boom which sprayed from the sides as 
well as from above, using three large chambered nozzles to the row. 
The pressure was kept at about seventy-five pounds. At this pressure 
fifty gallons of liquid was required to cover an acre. 
ARRANGEMENT OF THE PLOTS 
Three fields having a total acreage of about twenty acres were 
available for this experiment. A little less than one half of the total 
area was planted with Early Ohios and the remainder with Rural New 
Yorkers. Since early potatoes as a rule seem to suffer more seriously 
from insect attacks than the later varieties, and since the Early Ohios 
were planted all together on a fairly uniform piece of ground, these 
were selected for the most intensive work. In the case of both the 
early and late varieties, the fields were divided into plots. These plots 
varied somewhat in size according to convenience. Each material 
was applied to two or more plots in the case of both early and late 
varieties, so as to eliminate as far as possible error due to soil varia- 
tion. 
STOMACH PoIsoNs 
The first set of arsenical sprays was applied to the early potatoes 
and to the late potatoes adjoining them on June 13 and 14. At 
this time, the plants in the early plots were eight inches high while 
those on the late plots were about six inches high. The adult potato 
beetles had been present on the plants for a week or more. Eggs were 
observed for the first time four days previous to spraying. None of 
the eggs were observed to have hatched at the time the first spray was 
applied, altho it is possible that some newly hatched larvae had 
