244 INSECTICIDES, FUNGICIDES, AND WEED KILLERS. 



treated this disease by sprayings of O'O and 0-75 per cent of bouillie 

 bordelaise with a sHght excess of lime. Girard found, by treating 

 beet-lields by a bouillie bordelaise with '6 per cent blue vitriol and 

 5 per cent lime, if not a total increase in the weight of the crop, at 

 least -^ per cent more sugar. On 35 acres, of which 4 per cent of the 

 beets were diseased, 5 hectoliti-es (110 gallons) of 3 per cent bouillie 

 gave the above good i-esults. 



Peronospora ganglifonnis, De By. (lettuce disease). — Sulphur, 

 formerly used by kitchen gardeners, having no action on this blight, 

 the mycelium of which lives in the interior of the leaves, it has been 

 tried to treat it with copper preparations. Young lettuce leaves are 

 very delicate. They require as much care as vine leaves, and the 

 bouillie must be prepared with great care. To be effective the treat- 

 ment must be preventive. When the bed is prepared, either for sow- 

 ing or transplanting, it is watered with a 4 per cent solution of 

 blue vitriol, or with a 4 per cent bouillie so as to reach all the 

 surface parts. The bed in contact with the plants is thus 

 disinfected. During growth a very neutral bouillie, made with 

 0"5 to 1 per cent of blue vitriol, is spread on the plants in the evening 

 or in cloudy weather. The effects are not so categoric as those ob- 

 tained in the treatment of mildew of the vine. The exceptionally 

 favourable conditions to the development of the Peronospora gangli- 

 formis created by kitchen gardening, its rapid growth demanding 

 several treatments close to one another, the fact that the conidia do 

 not give rise to the formation of zoospores, generally ten times more 

 sensitive to copper salts than the conidia themselves, are the causes of 

 some failures. 



Peronos2)ora Viscine, De By. (mildew of the pea and the bean). — 

 Treated by spraying as soon as the spots appear on the leaf. 



Peronospora arborescens, De By. (mildew of the poppy). — Treated 

 by bouillie bordelaise before the appearance of the disease (Nijpels). 



PeronosjMra Schleideni, Ung. (mildew of the onion). — Spraying 

 with bouillie is effective (Nijpels). 



To sum up, bouillie bordelaise forms an excellent means for treating 

 and preventing mildews. These diseases all have the same method 

 of dissemination by summer spores which enables them to become 

 deadly to crops in a comparatively short time, especially in a moist, 

 warm season. They should be treated preventively by bouillie borde- 

 laise at the moment the first symptoms of the disease appear, or better 

 still, before their aj^pearance at the epochs propitious for the rapid 

 spread of this fungus. Applied wath care bouillie bordelaise always 

 gives a perceptible and useful result, paying liberally for the cost of 

 the treatment. A single spraying cannot produce immunity for the 

 whole year, and if it be desired to preserve the plants from all attacks 

 this treatment should be applied judiciously each time that the weather 

 is favourable to a deadly extension of this fungus. 



Plasinopara cuhensis, B. et C. (mildew of the cucurbitaceae). — This 

 fungus attacks Cucumus sativus, Melo cucurbita maxima, GitriUlus 

 vulgaris. — It may be treated by bouillies bordelaises repeated several 

 times a year. Selby, Halsted, Sirrine, and Stewart obtained good 



