FUNGI. 365 



less ; and if a great excess is used, the leaves of the vines will 

 be damaged : therefore the application of sulphur requires judgment 

 and skill. 



Mr. Gassiot pointed out many years ago that the cost of the flour 

 of sulphur in vineyards would be more than the fee simple of the 

 estate on which the vines were grown. 



Unlike the fungus attacks of the potato, beet, turnips, or cabbages, 

 I have never seen the grape-vine fungus preceded by the puncture 

 of any aphis, and perhaps it lives more upon the exterior of the 

 plant than on its inner structure. 



Closely allied to the grape-vine fungus, we have various species of 

 the genus Erysiphe, attacking the hops and other plants. E. pisi 

 or Martii (fig. 848). lives upon the leaves of peas, and is very trouble- 

 some to the gardener. It is only in the latter part of the year that 

 this pest is so destructive, and at my garden we suffer most severely 

 from the pea mildew in dry autumns, when the whole haulm looks 

 as though it were dusted over with fine chalk : when this occurs, 

 the cultivation of the pea is impossible, as there is no known remedy 

 for this disease. 



FIG. 848. Erysiphe Martii, FIG. 849. Sphaerotheca pannosa, 



with Spores magnified. with Spores magnified. 



Although our rose-trees are generally the very picture of health, 

 yet they are occasionally stricken with blight, and the leaves look 

 as if they had been dusted over with flour. This species of fungus 

 is called the Sphcerotheca pannosa (fig. 849). It is supposed to be a 

 condition of O'idium leucoconium. 



In the year 1871 the hybrid perpetual rose-trees were much affected 

 by a red fungus (Coleosporium pingjie, fig. 850). The leaves which 

 were attacked prematurely dropped. It was first observed at the end 



