186 INSECTICIDES, FUKGICIDES, AND WEED KILLERS. 



his opinion of sterilizing the cankers produced by anthracnose, green 

 vitriol employed pure is perfectly capable of giving excellent results ; 

 moreover, it has the advantage over 10 per cent sulphuric acid solutions- 

 of not scorching the buds, and only retarding their unfolding slightly. 

 If the addition of blue vitriol be not injurious, and if mixtures contain- 

 ing this product have given excellent results in the Haute-Garonne, 

 this salt is not indispensable, and adds to the cost of the treatment. 

 To-day 50 per cent solutions of green vitriol acidulated by sulphuric 

 acid are in constant use in the Bordelais; they are inclu4ed in the 

 annual ti'eatment of vines in Medoc, and in all districts which suffer 

 from anthracnose. The green vitriol solutions are made thus : 

 50 kilogrammes (110 lb.) of green vitriol are placed in a wooden or 

 stoneware vat, then mixed with 1 litre of sulphuric acid of 53" B. 

 Whilst stirring with a stick 100 litres (22 gallons) of hot water are run 

 into the receiver. The precaution of first mixing the green vitriol 

 crystals with the sulphuric acid is necessary to avoid projection of 

 corrosive liquid. The solution is applied hot to prevent crystallization 

 on cooling. The stock is coated with a big brush, or with a plug of 

 rags attached to the end of a wooden handle, then all the stock, the 

 stem, the arms, and the runners are soaked without respecting the eyes. 

 However, it is necessary to coat from below upwards so as not tO' 

 scorch the buds ; it is also preferable to unbark the stock before using 

 this corrosive liquid. The operation should always be carried out 

 during the repose of vegetation ; it is a winter treatment which is best 

 done twice with fifteen days' interval ; the last operation takes place- 

 fifteen days before the opening of the leaf, that is to say, at the moment 

 the spores germinate. The best season is therefore the end of Febru- 

 ary or the beginning of March, but often this treatment is applied at 

 the moment the buds begin to open. After coating the wood should 

 become black. If rain ensue and this change has not taken place the 

 treatment must be repeated. Green vitriol solutions in no way attack 

 the buds, but none the less retard their opening fifteen days. The 

 districts where anthracnose prevails suffer much from frost, and this 

 retardation of vegetation is very beneficial to the vine. The operation 

 should be done in calna weather so as to avoid too great evaporation 

 of the solution. It takes 8-10 litres (1-76-2-2 gallons) of this solution 

 for 1000 stocks of vines. Spraying may be used with great advantage, 

 the work is done quicker than with the brush, but it involves the use 

 of tools with glass reservoirs. When anthracnose is developed during 

 plant growth, it is contended against by mixtures of sulphur and green 

 vitriol in powder ; this treatment stops the development of the spores, 

 but it should be renewed several times to protect the vine; it is, in 

 fact, a preventive rather than a curative method. 



Ophiobolns graminis, Sacc. (disease of the stem of wheat). — This 

 disease may be avoided by burying in the soil 80 kilogrammes of green 

 vitriol per hectare (70-4 lb. per acre) (McAlpine). 



Dothichiza populea. — To prevent infection through wounds it is 

 sufiicient to coat them with a solution of 10 per cent of green vitriol 

 and to cover them with a mastic. 



Use of Green Vitriol against Insects. — AntJwnomus pomoriim. 



