BOUILLIE BOEDELAISE. 



251 



and cause irreparable damage in forty-eight hours. The time of 

 treatment should thus be chosen with circumspection, and the number 

 of sprayings subordinated to weather favourable to the evolution of the 

 parasite in question. Whilst dry, cold weather may completely stop 

 black rot, on the other hand, moist, warm weather gives it full scope. 

 It is therefore at such a time that it is most advisable to spray, and con- 

 tinue to do so at very short intervals. If in most cases three sprayings 

 suf&ce, seven to ten are required in moist seasons (Prillieux and Viala). 

 Dussuc advises the use of the following sprays : — 



TABLE XLYI.—Sh'nving the Composition, Volume Per Acre, Time of Treat- 

 ment, and Order of Sequence of Bouillies Bordelaises used in the Pre- 

 vention of Black Rot of Grapes. 



Dussuc believes the above gradually increasing quantities, used 

 at the different times of spraying, are indispensable, so as to cover 

 the entire surface of all the green parts of the vine. One of the 

 essential conditions of success rests, in fact, on the care taken to spare 

 neither the upper nor under surface of the leaves. When the vines have 

 tufts which prevent the uniform penetration of the liquid, they should 

 be further treated with powders containing blue vitriol and sulphur. 

 By alternating the spraying with bouillie bordelaise and with powders, 

 the results obtained leave nothing to be desired. Lamson, Scribner, 

 and Pearson recommend, in America, four to five sprayings, the first 

 of which is made on 5 May, and the last in autumn. Trials on the 

 large scale made in America by 250 vine-growers secured to them a 

 profit of £7400 (Galloway). The 4-6 per cent bouillies, used in the 

 beginning, are now abandoned and replaced by 2-3 per cent bouillies. 

 In France four treatments are the rule, and should be applied at the 

 following periods in most instances (Couderc) : — 



TABLE ^yLWl.—Shoiving Order, Time of Spraying, and Strength of Bouillies 

 in Treatment of Black 'Rot of Grapes (Couderc), 



