FUNGICIDES. 



1. BORDEAUX MIXTURE. 



4 pounds copper sulfate (blue vitriol). 

 4 pounds lime (unslaked). 

 25 to 50 gallons water. 



Dissolve the copper in hot or cold water, using a wood or earthern 

 vessel. Slake the lime in a tub, adding the water cautiously and 

 only in sufficient amount to insure thorough slaking. After thor- 

 oughly slaking, more water can be added and stirred in until it has 

 the consistency of thick cream. When both are cold, dilute each to 

 the required strength and pour both together in a separate receptacle 

 and thoroughly mix. Before using, strain through a fine mesh sieve 

 or a gunny cloth. 



The mixture is then ready for use. Considerable trouble has fre- 

 quently been experienced in preparing the Bordeaux Mixture. Care 

 should be taken that the lime is of good quality and well burned and 

 has not been air slaked. Lumps are far superior to the fine lime 

 and such are selected by masons for preparing finishing coats. 

 Where small amounts of lime are slaked it is advisable to use hot 

 water. The lime should not be allowed to become dry in slaking, 

 neither should it become entirely submerged in water. Lime slakes 

 best when supplied with just enough water to develop a large amount 

 of heat which renders the process active. If the amount of lime in 

 the Bordeaux Mixture is insufficient, there is danger of burning ten- 

 der foliage. In order to obviate this the mixture can be tested with 

 a knife blade or with ferro-cyanide of potassium (i oz. to 5 or 6 oz. 

 of water). If the amount of lime is insufficient, copper will be 

 deposited on the knife blade, while a deep brownish-red color will 

 be imparted to the mixture when ferro-cyanide of potassium is added. 

 Lime should be added until neither reaction occurs. A slight excess 

 of lime, however, is desirable and it is seldom one has to apply these 

 tests. 



The standard mixtures are : 



(a). 25 gallons (full strength mixture, or 4 — 4 — 25 formula), 

 that is 4 lbs. copper sulfate, 4 lbs. lime and 25 gallons 

 water. 



