48 INSECTICIDES, FUXGICIDES, AND WEED KILLERS. 



Halsted estimates that manure with 170 kilogrammes of sulphur per 

 hectare, say 150 lb. per acre, especially if it be accompanied with a 

 manuring of 175 kilogrammes per hectare (154: lb. per acre) of kaiuit, 

 gives results quite as satisfactory as the usual disinfection of the 

 tubers by corrosive sublimate. 



Nijpels, who controlled these experiments, found, however, that 

 his own process gave a better result. 



Use against Fungi. — Amongst the PeroiiosjMva we may quote 

 Cystopus Gandidiis, Lev. (white rust of the Cruciferge) ; Cyitojnis 

 cubicus, de By (white rust of the Composite). The sulphuring re- 

 commended bj' Weiss to combat white rust can have no effect, except 

 preventively, at the time of lifting the seed. Then several sulphurings 

 are applied, working preferably in the morning during the dew. 



UredinecB (rusts injurious to cereals). — Sulphur has no action on 

 these diseases, the mycelium of which grows exclusively in the body 

 of the nurse plant, and the spores of which are generally formed 

 under the epidermis of the plant. The failure of Galloway, Hitch- 

 cock, Carleton, and Kellermann, was, therefore, to be foreseen. To 

 disinfect the soil of these fields, as well as the wheat seed already 

 sown, and prevent rust, Galloway tried burying sulphur in large 

 quantities underground, but there was no improvement. These ex- 

 periments, in fact, had no chance of succeeding, for it is known that 

 the fungi of rust are heteroic, that is to say, they possess different 

 methods of reproduction, which succeed each other during the course 

 of the year on different plants in a determined order. Thus the 

 barberry carries a form of fructification of the rust of wheat known 

 under the name of Aecidium. The infection of the fields does not 

 come from the seed but from the neighbourhood of certain special 

 plants. Amongst the Erysijjhe we may quote Erysiphe communis, 

 Wallr. (mildew of the pea and bean). We can efficiently contend 

 against this fungus, either by the use of sulphur or of sulphur 

 and lime. Prillieux holds that sulphuring done as soon as the 

 first spots appear may completely save the crop invaded. In the 

 same category the most important of all the diseases, that which 

 has caused the greatest ravages, is, without doubt, the disease 

 known under the name of Uncinula Americana, How. (oidium 

 of the vine). Since the decisive researches of Mares, vine-grower of 

 Herault, it has been possible owing to the use of sulphur to -contend 

 victoriously against this plague without, however, causing it to dis- 

 appear completely. It is quite as lively as when it first appeared, but 

 by the rational application of sulphur its development can be circum- 

 scribed and its action on crops prevented. The disease always assumes 

 new vigour when vine-growers are negligent in the execution of this 

 treatment. But so that the latter may be absolutely efficient, it must 

 be practised in special conditions. It is evidently difficult to fix in a 

 precise manner for all I'egions the number of sulphurings to apply 

 and the proper times, so as to protect the vine from invasion. Mois- 

 ture and heat are, in fact, important factors of the development of the 

 oidium ; the question of climate, of .exposure, of the year itself, have a 

 great influence on the time of treatments and their number. There 



