REPORT OP COMMITTEE ON PUBLICATION 153 



Bordeaux mixture met with in practice differ, therefore, more or less mark- 

 edly from one another, both as regards physical constitution and chemical 

 composition shortly after they have been made, as is indicated in the follow- 

 ing table in which the general characteristics of these washes, both at the 

 time of preparation and after no further change takes place, are briefly 

 shown: 



Table II. Chief characteristics of the Bordeaux mixture types when pre- 

 pared and after standing until a state of equilibrium has been reached. 



Per cent Ratio 



Type of Mixture Cupric Cupric Sulphate Color of Mixture 



Used Sulphate Calcic Oxide When Fresh 



"Acid" Bordeaux Mixture 1% 1:0.2 approximately Cendre bluei 

 "Neutral" " 1% 1:0.25 approximately Cendre blue 



Alkaline " 1% 1:0.5 Light cerulean blue 



Strongly alk. Bordx. Mix. 1% 1:1 Light methyl blue 



Color of Mixture 



Form of Precipitate Composition of Precipitate 



When Old Fresh Mixture Old Mixture Fresh Mixture Old Mixture 



Deep medici blue Gelatinous Flocculent 10 CuO SO 3 CuO largely 



Light medici blue Gelatinous Flocculent 10 CuO SO 3 CuO largely 



Bradley's blue Gelatinous Crystalline 10 CuO SO 3 ? 



Light amparo blue....Gelatinous Crystalline 10 CuO SO 3 ? 



Having obtained a knowledge of the general charateristics of the Bor- 

 deaux mixtures met with in practice, we may now proceed to study their 

 relative value as fungicides taking up for consideration first the action of 

 these washes on the plant to be protected, i. e., the grape vine. 



in. 



The effect of the Bordeaux mixtures on the grape vine may be neutral, 

 beneficial, or more rarely deleterious. I shall not attempt to consider the 

 cause of the beneficial action that follows the use of a Bordeaux mixture 

 as it would lead us too far afield to do so. Suffice it to say that this bene- 

 ficial action, the most obvious feature of which is the darker green color of 

 the sprayed foliage, appears to be more marked when alkaline Bordeaux 

 mixtures are used then when "acid" or "neutral" Bordeaux mixtures are 

 employed. The toxic action of Bordeaux mixtures, on the other hand, is 

 only produced when alkaline washes are employed and is confined, so far 

 as I am aware, to young and growing leaves. All varieties of the grape are 

 not equally sensitive, however, to the action of alkaline Bordeaux mixture 

 and furthermore, if we are to believe Ewart* injury is either produced within 

 24-48 hours, or is not produced at all. 



i Ridway, R. Color standards and nomenclature. Washington, D. C., 

 1912. The colors are to be viewed on a white ground. 



3 The statements I shall make during the course of the present chapter 

 are not to be considered as applying either in whole or in part to the effects 

 produced by Bordeaux mixtures on other plants. Whether they will be the 

 same, or whether they will be different, experiment alone can tell. 



4 Ewert K. Die fungicide und nhysiologische Wirkung der Kupferhaltigen 

 Bruhen mit besonderer Beriichsichtigung der Bordeauxbruhe, Mitteilungen 

 des Deutschen Weinbau-Vereins 2, 1907. 



