1893.] PUBLIC DOCUMENT — No. 33. 239 



England is concerned, the season has been far less fiivorable 

 to the development of the rust fungi than in previous years. 

 The losses appear to have l)een very light from this cause, 

 and it has not been possible to obtain data of value concerning 

 them. The only crop distinctly mentioned as suffering at 

 all has been oats, and it is by no means certain that the 

 cause of its affection was one of the species of Puccima to 

 which the true rusting of grain is due. The season of 1892 

 must, therefore, be set down as one of unfavorable condi- 

 tions and negative results in New England. 



V. Notes on Various Diseases. 



1. The Powdery Mildew of tije Strawberry (Sphce- 

 roilieca Castagnei Lev. ?) (PL III.) Avas brought to my 

 attention on the experimental plats of the Agricultural 

 College, early last summer. The affection shows itself in 

 a peculiar curling or inrolling of the leaves, which causes 

 them to take a somewhat cup-like form. If the lower 

 surfaces of the curled leaves be carefully examined, they 

 will be seen to be frosted by minute white threads scattered 

 rather sparingly over them. They are not grouped in more 

 or less circumscribed spots, like those of the similar mildew 

 of the cucumber, previously described. But microscopic 

 examination shows that their structure is essentially like 

 those of the " OicUum" form of the latter. Erect threads 

 arising from the mycelium (fig. 20) cut off the summer 

 spores from their ends in basi petal succession, and these fall 

 off as they mature (fig. 21). The form and size of these 

 spores (fig. 22) confirm the impression produced by the 

 habit of growth that we have here to do with a species quite 

 distinct from that which attacks the cucumber. Although I 

 have not observed the perfect spore form, it is probable that 

 the fungus with which we have here to do is Sphcerofheca 

 Ca.stagnei. 



This fungus does not appear to be very destructive to the 

 strawberry, or to have attracted much attention. It has 

 been briefly described by Arthur,* who observed it in New 

 York. He found it attacking the fruit as well as the foliage, 



* Fifth Report New York Experiment Station, p. 291, 1887. 



