Diseases of Plants 297 
and then dissolved in 6 quarts of water. When the lime 
is well dissolved mix the two solutions, strain, and use 
immediately. 
Weaker solutions, such as a 2—4—50 formula, are often 
prepared for use on 
young plants and on 
tender crops that are 
injured by the stronger 
solutions. 
Sometimes the lime 
is of poor quality or has 
lost its strength, or the 
copper may be so strong 
that it “ burns ”’ leaves 
that it touches. The 
solution may be tested 
as follows: Dip a clean, 
bright steel knife blade 
into the prepared solu- 
tion for 30 seconds. If 
it is “‘ coppery ” in color 
when removed, there is 
not enough lime, and 
lime water should be 
added until the knife 
blade does not “ cop- 
per ” when tested. 
When this poison is 
sprayed on the surface of 
leaves, it kills the ger- 
minating spores which 
Fic. 167. The proper way to carry a 
compressed-air sprayer of the knapsack 
type. The strap goes over the left shoulder, 
and the tank is partially supported by the 
right hand. 
