BOUILLIE BOEDELAISE. 245 



results. The latter produced by this ti'eatment 102,000 vegetable 

 marrows instead of 20,000 on an untreated plot of the same 

 size. 



UstilaginecB. — After the fortunate results obtained by vitriolizing 

 corn-seed by Kuhn's method, consisting in steeping in a solution of 

 blue vitriol followed by washing in milk of lime, it was interesting to 

 treat corn-seed with bouillie bordelaise. Experiments in this direction 

 show that the action of cupric hydrate is, so to speak, nil. That is 

 not at all surprising seeing that the spores of the Ustiiaginea are much 

 more resistant to copper compounds than the spores of the Perono- 

 S'porece. In treating the different mildews the object of spraying with 

 bouilhe bordelaise is to prevent the spores from germinating and 

 penetrating into the vulnerable organs. The bouillie borJelaise can- 

 not destroy the very resistant zoospores or dormant spores but only 

 the extremely sensitive zoospores. Besides it cannot kill the winter 

 spores of the UstilaginecB which infect grain, and only in an indifferent 

 manner hinders their germination ; it cannot, therefore, prevent them 

 from penetrating into the young plant which it does not protect. 

 Hence Kellermann and Swingle declare after many trials that bouillie 

 bordelaise cannot replace blue vitriol in the disinfection of corn-seed. 

 Bedfort obtained the same negative result. After steepiu'^ oats-seed 

 in bouillie bordelaise made with 2 per cent blue vitriol and 2 per cent 

 lime there were as many "rust " ears as sound ears, whilst seed from 

 the same source disinfected the same day by 2 per cent formaline pro- 

 duced no diseased ears. In the preventive treatment of Ustilago 

 viaydis, Corda (rust of maize), Halsted found a diminution in the 

 disease but not its total suppression. Bouillie bordelaise cannot, there- 

 fore, as recommended by Van Tabeuf, replace blue vitriol in the disin- 

 fection of corn-seed. 



Uredinea (rusts). — Bouillie bordelaise has been used with greater 

 or less success to treat some species of rust. The object of spray- 

 ing with the bouillie bordelaise was to prevent the summer spores of 

 the aecidium and uredo from germinating and spreading the disease. 

 Bouillie bordelaise cannot be used practically to combat the more 

 deadly rusts. 



Busts of Cereals. — Numerous trials by Galloway, Swingle, and 

 Bartholomew, both with bouillie bordelaise and cupric borate, cupric 

 ferrocyanide or eau celeste, trials which consisted in practically spray- 

 ing every ten days the whole plant, gave no satisfactory result. This 

 check is attributed to — 



1. The difficult adherence of the bouillie oa the cereal grain. 

 Even if sugar, gum, or glue be mixed with bouillie bordelaise, the 

 plant cannot be covered with a layer of cupric hydrate capable of pre- 

 venting the germination of the spores to be found there. 



2. The sti^ength of the ordinary bouillies, 0-5-2 per cent, which is 

 quite insufficient. To obtain an appreciable result very strong bouillies 

 must be used, made with about 8 per cent of blue vitriol. These 

 might have an immunizing action on cereals, and prevent the disease, 

 if the great expense and the practical difficulty did not remove this 

 treatment from cultural methods. Galloway, Kellermann, and Cobb 



