84 
Colorado Experiment Station 
varieties from any given variety by selecting resistant individuals 
from heavily diseased fields. It was by this method that wilt-re- 
sistant fiax, blight-resistant tomatoes, and varieties of cabbage 
resistant to yellows were produced. 
The production of disease-resistant plants is a slow, difficult and 
expensive task and is one that must, for the most part, be left to the 
Experimental Stations. 
PREPARATION AND APPLICATION OF SPRAYS AND 
OTHER FUNGICIDES 
Bordeaux Mixture 
This is one of the oldest and best known fungicides. It is perhaps 
the most valuable spray known for the control of plant diseases. 
Bordeaux mixture is prepared by mixing a solution of copper-sulfate 
(blue vitriol) with a solution of stone lime slaked in water. For 
example, Bordeaux mixture (4-5-50) means that 4 pounds of copper- 
sulfate and 5 pounds of lime are used to 50 gallons of water. The 
quality of Bordeaux mixture depends greatly upon the manner in 
which it is prepared. Bordeaux mixture improperly prepared is 
worthless. The copper-sulfate and the lime must be dissolved sepa- 
rately and mixed just before using. After the two solutions are 
mixed they should be used at once, as Bordeaux mixture loses its 
strength in a very short time. Stock solutions may be prepared by 
dissolving each ingredient in a small quantity of water. These solu- 
tions should be diluted to the proper strength and mixed when 
ready for use. The following directions may serve as a guide for 
the preparation of 50 gallons of (4-5-50) Bordeaux mixture. 
The quantities of material may vary with the strength and 
quantity of solution desired. 
Materials : 
Copper-sulfate (bluestone) 4 pounds 
Stone lime 5 pounds 
Water 50 gallons 
Apparatus : 
2 half-barrel tubs with capacity of about 30 gallons, made by 
sawing a 60-gallon barrel through the middle. 
1 60-gallon mixing barrel. 
2 or more wooden pails. 
1 strong paddle about 6 feet long for stirring the mixture. 
1 pair of hand scales for weighing materials. 
1 strainer of cloth or 20 mesh brass gauze. 
