No. 244. J 239 



Other common instances of injurious parasitic growths occur in the 

 mildew on the fruit and foliage of the grape, which likewise infests 

 destructively, many other trees and fruits. 



Another, which seems to me of comparatively recent occurrence, I 

 have noticed for these ten or fifteen years past, during wliich time it 

 has made great progress in destructiveness. I have noticed it chiefly 

 on the foliage of several species of the genus Rubus. It is a fungus 

 of a bright orange color, and infests the under side of the foliage of 

 the common red raspberry, Rubus ideus, in Connecticut ; and the ex- 

 haustion occasioned by this fungus, causes the plant to put up a mul- 

 titude of spindling stalks, and renders it wholly unprolific. This af- 

 fection disseminates itself, and I know of no remedy for it. 



The trailing wild blackberry (Rubus trivialis) is attended with a 

 similar parasitic infliction on its foliage, and I have seen half an acre 

 of ground wholly occupied by this vine, and so. stinted in growth by 

 this iron rust fungus as not to bear any fruit. 



But the most interesting to us on this occasion of the different or- 

 ders of vegetable formations which become attached parasitically to 

 the wood, foliage and the fruit ol trees, and growing on them, is a 

 species of an extensive tribe which, in sections where prevalent, at- 

 taches to the fruit of the pear andapple, and occasionally to the peach. 

 It appears in the form of dark spots, or of a number of dark brown 

 dots or patches on the surface of the fruit. On some fruit it exists 

 without producing any very apparent effect, but is a blemish, while in 

 others it produces a slight depression, and on others it destroys the fruit, 

 by causing it to crack in every direction. 



It is to this cause, I am convinced, may be attributed the cracking 

 of the white Doyenne pear, by which, in some sections, it is rendered 

 quite worthless. The reason it operates more destructively on this 

 than on any other variety, is probably that the skin of this pear is of 

 such a texture at the time when this parasite sheds its seminal prin- 

 ciples, as to be most favorable to their reception and germination, 

 and afterwards to its growth, and penetrating beneath the parenchyma, 

 a substance of the fruit, the parts contiguous being thereby deprived 

 of vitality, shrink, and drying, become hard, thus stinting the growth 

 of the fruit, and often occupying the whole surface of it with hard 

 cracked cicatrices, rendering it wholly inedible. This malady affects 



