POTALTO-SPRAVING IN MINNESOTA 
By S. A. GRAHAM 
In the past, it has been the custom of the Division of Entomology, 
in testing insecticides, to carry on the preliminary tests on small plots 
at University Farm and if these proved satisfactory, to make tests 
on a larger scale in co-operative experiments with farmers in different 
parts of the state. For several practicai reasons, this system of leav- 
ing the final tests to farmers, even with careful supervision, has not 
proved satisfactory. Since tests on a large scale are absolutely neces- 
sary in order that questions may be intelligently and authoritatively an- 
swered, and since there was not sufficient available land on or near 
University Farm for such experiments, it was decided in the spring 
ef 1918 to try a modification of the old co-operative scheme for the 
potato spraying experiments which promised to avoid most of the diff- 
culties encountered in past seasons. 
The greatest difficulty in the past has been to get the materials on 
the plants at exactly the proper time and in the right way, particularly 
since most of the experiments were located at some distance from the 
Station and often in more than one locality. It was also difficult or 
impossible to get comparative data on a number of different insecticides 
under the ordinary co-operative agreement. From past experience it 
seemed advisable to keep the following points in mind. 
(1) All spraying and mixing of materials should be done by 
someone connected with the Experiment Station and not by the farm- 
er. (2) All observations should be made by a man connected with 
the Experiment Station. (3) The spraying should be done with a 
standard type of traction spraying machine which should be available 
at a moment’s notice. (4) The spraying experiments should all be 
located in the same locality, preferably on land owned by a single 
person, and readily accessible from University Farm. 
After some searching, a suitable location was found and the fol- 
lowing verbal agreement was made with the owner of the farm. 
The owner agreed to: 
1. Plow and harrow the soil and plant the potatoes in three foot 
rows. 
1 Published with the approval of the Director as Paper No. 158 of the Journal 
Series of the Minnesota Agricultural Experiment Station. 
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