GEEEN VITRIOL. 181 



sfcroying cryptogam ic germs ; and (4) preserving vines from frost. But 

 to attain this end, instead of only coating the sections the whole stock 

 must be coated from top to bottom with a 30-40 per cent solution of 

 gL-een vitriol. This treatment, which is done in this case in the autumn, 

 retards from ten to twelve days the exit of the buds and may thus pre- 

 serve the viae from late frosts. Used on the large scale in Cognac and 

 Charente this process gives most precise and satisfactory results. 

 Andre has adapted the Eassiguier treatment to fruit trees. After 

 autumn pruning he coats the same day the sections and all the wood 

 with a 30 per cent solution of green vitriol. This process, very effec- 

 tive on young trees attacked by chlorosis, is not energetic enough for 

 large trees, on which it is necessary to decapitate the branches and to 

 make slight incisions in the bark of the base of these branches. By 

 means of a brush a 30 per cent solution of green vitriol is caused to pene- 

 trate as far as the sapwood. These coats should be applied at intervals 

 ■of eight days. Favourable results were got chiefly on cherry-trees, pear- 

 trees, and peach-trees ; the yield in fruit is much increased, and amongst 

 the latter the rust completely disappears. Green vitriol can thus be 

 entrained by the sap without injuring the plant. Very interesting trials 

 by Mokrzecki conducted thus confirm this fact : He pierced one or several 

 holes in the trunk of the tree and there introduced green vitriol in 

 crystals, then closed the holes with mastic. An average dose of 12 

 grammes suffices to suppress chlorosis. 



(C) Use as an Injection in the Trunk. — The satisfactory re- 

 sults obtained by the extra-racinary nutrition of trees and by the 

 injection of nutritive salts into the sapwood of the trunk induced 

 Mokrzecki to hope to cure chlorosis by injection of solutions of green 

 vitriol into the sap. He pierced one or more holes of 1-1-75 centi- 

 metres (f-yV inches) in diameter in the trunk and injected 12 grammes 

 of green vitriol in 0-0o-0-25 per cent solution. So that the 

 solution may be entrained by the sap it is of importance to prevent 

 access of air ^ into the hole during the time it is being pierced. 

 To accomplish this it is necessary to proceed as follows : The 

 point of the centre-bit is passed through a metal tube which com- 

 municates by an india-rubber pipe with the reservoir containing the 

 green vitriol solution. By working the centre-bit the liquid forthwith 

 fills the space drilled out and thus prevents the access of the ambient 

 air. The reservoir is hung to a branch and the liquid thus introduced 

 under a certain pressure. The holes are pierced through the sapwood. 

 A tree with a diameter of 20 centimetres (8 inches) is capable of ab- 

 sorbing 8 litres (1| gallons) in twenty-four hours. As soon as the 

 operation is finished the hole is refilled with mastic. The most favour- 

 able time for this work is the months of March, April, or May, when 

 the sap is in motion. Trees attacked with chlorosis show from the 

 fourth day a greener colour in their leaves ; in ten days chlorosis is no 

 longer to be seen, and in three weeks the leaves are deep green. Trials 

 made on 840 trees leave no doubt of the etficiency of this treatment. 

 During his experiments Mokrzecki also observed that all the organs of 



^ The appliances formerly used by Bouchery, Hartig, Pichi, and Berlese allowed 

 air to penetrate which prevented the absorption of the liquid. 



