266 INSECTICIDES, FUNGICIDES, AND WEED KILLERS. 



overcome this disease in full evolution, 3 lb. blue vitriol, 1 lb. 80-85 

 per cent soda ash, and 12 fl. oz. of ammonia of 24° B. in 10 ^'allons of 

 water. Spraying is done in the morning as soon as the dew has 

 evaporated. A dilute solution, used in July, will not burn the leaves. 



Pcronospora viticola, De By. (mildew of vine). — Eau celeste affords 

 cheap summer treatment, especially to stop a sudden outbreak. Mohr 

 advises for June spraying an eau celeste prepared thus : Dissolve 1 .^ lb. 

 of blue vitriol in 2 gallons of water, add first 8 fl. oz. of ammonia, 24° B., 

 then the solution of | lb. of 80 per cent soda ash, and make up to lO' 

 gallons. July and August sprayings are made with an eau celeste con- 

 sisting of 2 lb. of blue vitriol, 9"6 fl. oz. of ammonia, 12 oz. of calcined 

 soia, and 10 gallons of water. In the opinion of several observers a 0-4 

 per cent eau celeste suffices. Prillieux doubts its efl&cacy and prefers 

 a stronger eau celeste to produce an effect on the disease in full evolu- 

 tion and an advantage over bouillie bordelaise. Kalas' results with 

 bouillie bordelaise are in a general way better than those obtained 

 with eau celeste. Vines strongly attacked by mildew are greener 

 after treatment with bouillie bordelaise than after eau celeste. 



Peronospora gangliformis, De By. (lettuce disease). — Kitchen 

 gardens often have to suffer from this disease. It would be pre- 

 vented, according to Prof. Maxime Cornu, by covering the soil with 

 a layer of shavings or straw, previously impregnated with eau celeste. 

 Dung from mushroom beds ought to be drenched with eau celeste, 

 then drained, before being used for lettuces. 



Puccinia grarninis, Pers. (rust of wheat). — Galloway has examined 

 the effect of eau celeste on the evolution of rust, and made the in- 

 teresting remark that winter wheat, treated every ten days by spraying- 

 with eau celeste, is completely freed from rust, whilst it remained 

 attacked when the sprayings were at twenty days' interval. In this 

 last case the diminution of diseased plants was only 33^ per cent. 

 These results were disputed by Swingle. 



Puccmia Pruni, Pers. (plum leaf rust). — Pierce reports that this- 

 rust is successfully overcome by an eau celeste of blue vitriol 1 lb., 

 ammonia 26° B. 12 fl. oz., carbonate of soda 1\ lb., in 100 litres of 

 water. 



Podosphcera OxycanthcB, D. C. — Pammel reports that he prevents 

 the fall of the leaves incidental to this disease by ten sprayings, from 

 6 June to 4 August, on grafted cherry-trees and Mahaleb plums 

 with eau celeste nwdifiee. The thirty-five plants treated had 4498 

 leaves against 1195 on the untreated samples. 



SpJuerotheca Ilumuli, Burr, (strawberry blight). — Humphrey ob- 

 tained a complete cure of attacked plants and a recrudescence of verdure 

 by treatment with bouillie bordelaise containing 0"4 per cent of car- 

 bonate of copper and 2 per cent of carbonate of ammonia. 



Guignardia Bidwelli, V. and E. (black i-ot of grapes). — Galloway 

 got good results by the following treatment : Modified eau celeste, 

 containing 0"1 per cent of copper carbonate dissolved in ammonia and 

 used in four sprayings, 30 April, 15 May, 30 May, and 14 June. The 

 total of the diseased grapes was reduced to 0'6 per cent, against 45 per 

 cent on the untreated stocks. 



