22 MASS. EXPERIMENT STATION BULLETIN 201. 



I. PROTECTIVE APPLICATIONS. 



1. Copper Fuxgicides. 



This group of fungicides owes its effectiveness to the action of dissolved 

 copper on the fungus. Copper sidjate was perhaps the first to come into 

 general use. Its use for disinfection of smutted grain seed was perfected 

 during the eighteenth century, and it is still used for that purpose in Europe 

 and Australia. 



Numerous copper ammonia washes have also been used with more or 

 less success, mostly for the diseases of ornamental plants. The best known 

 and most widely used of these washes are Eau celeste (cuprammonium 

 sulfate) and ammoniacal copper carbonate. Since none of them has come 

 into general use for farm or orchard crops, they need not be discussed 

 further at this time. 



The most popular and most extensively used of all copper fungicides 

 is Bordeaux mixture. Home-made Bordeaux and commercial Bordeaux 

 preparations are discussed separately below. Other copper fungicides 

 have not been used enough to warrant separate discussion at this time. 



(1) Bordeaux Mixture. 



A thick paste made by mixing slaked Ume with copper sulfate and 

 applied to the grapevines of southern France for the purpose of warding 

 off pilfering vagrants was the origin of Bordeaux mixture. Millardet, a 

 professor of botany at Bordeaux, observed that the vines which were so 

 treated suffered less from the downy mildew {Plasmopora viticola), which 

 had been introduced from America into France about 1878. He began 

 investigations, the results of which were published from 1882-85, and gave 

 to the world its most widely used fungicide. The whole science of pro- 

 ^tective spraying began with his work. Soon after the effectiveness of 

 Bordeaux mixture in controlUng grape mildew had been demonstrated 

 it was used with equal success for potato mildew and black rot of grape. 

 In 1887 it was introduced into the United States by the United States 

 Department of Agriculture, and its use extended to other diseases, until 

 by the end of the century it had come to be regarded almost as a panacea 

 for all fungous diseases of plants. 



Formulas. — Bordeaux mixture as now used is still made from lime, 

 copper sulfate (blue vitriol or bluestone) and water, but many different 

 formulas for the proportions of the three ingredients have been proposed 

 and used with success for various diseases. For Massachusetts crops and 

 conditions the "4-4-50 formula" (4 pounds copper sulfate, 4 pounds 

 cjuicklime and 50 gallons of water) is preferred, except in the case of the 

 late sprays for potatoes and the spray for celery and grapes. In the latter 

 cases 5-5-50 is recommended. Other formulas sometimes employed are 

 3-3-50, 5-4-50 and 6-4-50. 



