A.—Potatoes in a plot treated with calcium chloride, M pound per square foot, before pianting time 
B—Potatoes in a plot treated with 1 per cent HgCl2,1 gallon per square foot, before planting time. 
The plot in the foreground was treated with formaldehyde 
C— General view of plots 1 to 20 before treatment in 1921, showing trenches, frames, and fence used 
to reduce possibility of reinfection by surface water or animals 
D.—Potatoes in plots treated with Bordeaux mixture before planting time. Plot on left treated with 
Bordeaux 16-16-60, 1 quart per square foot, plot on right with Bordeaux 8-8-50, 2 quarts per square 
foot. Small parts of barren plots treated with copper sulphate and sodium fluoride respectively shown 
in the foreground 
