DILUTE SULPHURIC ACID AS A FUNGICIDE. 



By henry KRAEMER. 

 (Read April 20, 1906.) 



Sulphur has been used as a disinfectant, or deodorant, since very 

 ancient times. In The Odyssey reference is made to the burning of 

 sulphur for this purpose. As a parasiticide, insecticide and fungicide 

 it is extensively used at the present time. 



The value of sulphur as a fungicide in destroying epiphytic 

 fungi, particularly the powdery mildews of the rose, vine, hop, etc., 

 is well known. Sulphur is also' sometimes used in destroying the 

 spores of endophytic fungi, or at least in preventing their growth. 

 As a fungicide sulphur is used or applied in several ways, (i) In 

 the sublimed form (flowers of sulphur) it is dusted on the plants. 

 (2) Both sublimed sulphur and ground roll-sulphur, or " brim- 

 stone " (flour of sulphur), are mixed with water to form a paste, 

 which is applied to the heating pipes in green-houses, the finely 

 divided vaporized sulphur thus produced collecting on the plants ; or 

 small pieces of roll-sulphur may be carefully heated on a sand bath, 

 the finely divided vaporized sulphur being distributed in the same 

 way ; or sulphur in the form of an impalpable powder known as 

 " ventilated sulphur " may be used, as in Germany and Italy where 

 it is used for fighting the vine blight. (3) Sulphur is also ap- 

 plied in combination with lime in the form of solution, as in the 

 " lime-sulphur " washes, these being solutions of a number of sul- 

 phides and lower sulphates of calcium. 



Sulphur is insoluble in water and is not affected by most reagents 

 under ordinary conditions, and of itself could not be considered to 

 have fungicidal properties. Nor is it likely that it exerts a me- 

 chanical action like certain of the insecticides, as pyrethrum flowers, 

 or insect powder, which act by closing the breathing pores of the 

 insects. The action of sulphur as a fungicide is probably due, then, 

 to certain compounds of sulphur which result from the manner of 



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