58 INSECTICIDES, FUNGICIDES, AND WEED KILLERS. 



beeu extirpated if the following procedure be adopted : Trench the ground 

 to 65 centimetres (2 feet 2 inches), then at a distance of 50 centimetres 

 (20 inches) apart in every direction dig holes of 50-60 centimeters (20- 

 24 inches) deep. Run into each 100 grammes (say 3^ oz.) say 40 

 kilogrammes (88 lb.) per acre, and close the holes quickly; the soil 

 must remain in this condition until the spring, when the new planta- 

 tion will be made. In vineyards reconstructed in that way the young 

 vine stocks yielded in the third year 30 hectolitres (660 gallons) ; the 

 fourth year, 110 hectolitres (2200 gallons) ; whilst the test vineyard 

 non-treated only gave 74 hectolitres (1528 gallons). Here is, by a re- 

 port of the Baden Botanical Station, a curious result obtained in onion- 

 growing. Soils, completely exhausted by the culture of this plant, 

 were appreciably improved by disinfection by carbon disulphide. 

 Holes 40 centimetres deep, bored 50 by 50 centimetres (20 inches) in 

 every direction, received 100-300 grammes of carbon disulphide, and the 

 produce, which had fallen to 14 units per square metre, was raised to 

 22 by the dose of 400-800 grammes per square metre, and to 26 by a 

 dose of 1000 grammes (2-2 lb.). These improvements, due to carbon 

 disulphide, are very surprising, and efforts have been made to ascertain 

 how this product acts on the soil, since it is void of any nutritive 

 function, and how it can be the cause of intense yields in an exhausted 

 soil.^ There are a large number of parasites, both insects and fungi, 

 which live in the soil at the expense of the plants, and looking at their 

 grand opportunities for multiplying when the same plant is grown 

 continuously for several years the exhaustion of the soil, it will be 

 readily understood, is due solely to this accumulation of parasites which, 

 attacking the plant by the roots, remove from it the means of nourish- 

 ing itself. Carbon disulphide, injected into the soil, by destroying all 

 these parasites, restores to the soil its primitive purity, and the plant, 

 undisturbed by parasites, develops normally, and profits, by fertilizers, 

 to give large crops. Carbon disulphide acts like the bare fallow, which 

 also remedies soil exhaustion. By suppressing food from the parasites 

 accumulated in the soil for a certain time the latter greatly disappear. 

 Carbon disulphide is more effective than bare fallow, and gives com- 

 plete and immediate results, because it enables the soil to be com- 

 pletely disinfected and to utilize it at once for a new crop. The in- 

 fection of the soil is caused by fungi : Dematophora necatrix, Hartig ; 

 Armillaria Mellea, Quelet ; Boesleria hyj)ogaea, Thum. et Pass. ; by the 

 A7iguillulides, Heterodera Schachtii, Schm., and H. Radicola, Gr., and 

 insects, the larvae of which take several years to accomplish their evolu- 

 tion, such as the Elaterides (click beetles), cockchafers, etc. All these 

 parasites multiply greatly, especially when they are omnivorous and not 

 disturbed by rotations ; they are, in themselves alone, capable of pre- 

 venting a plant from producing normal crops. Carbon disulphide in 

 large doses creates in the soil a sufficiently poisonous atmosphere to kill 

 them, and so sterilize the ground being cropped. Contrary to Foex, 

 Dufour, Oberlin, and Couanon, whose researches leave no doubt as to 

 the action of carbon disulphideon the mycelium of different cryptogams, 



1 Note by Translator. — The onion is a sulphur-loving plant. The reason for 

 increase in crop is obvious. 



