REPORTS OF AUXILIARY SOCIETIES. 267 



are highly injurious to the species upon which they grow, and in some 

 instances have almost entirely destroyed crops infested hy tliern, as happened 

 some years ago with the onion crop in portions of Connecticut, (xathering 

 and burning the affected plants would, if it were practicable, be the most 

 effective means of cliecking tlieir ravages, and in the case of corn smut, which 

 in some localities is becoming a serious pest, this could be done without great 

 expense. As very few of the smuts have ever been reported upon woody plants 

 they may be passed without further notice. 



BLIGHTS OR WHITE MILDEWS. 



Still another class of fungi includes a multitude of species, some of which 

 popularly called "blights," have proved highly injurious to a number of our 

 most important fruit-bearing trees.* The white mildew on cherry and apple 

 leaves, Fodosplucra Kunzei, is of common occurrence in Michigan, and is the 

 cause of much injury when it attacks seedlings in nurseries. It covers a large 

 part of both the upper and lower surfaces of the leaves with its white filaments, 

 smothering and choking them, and in this way interfering with the normal 

 growth of the young trees. The mildew of gooseberries, Sphcerotheca panosa, 

 was observed in the summer of 1881, growing abundantly on wild gooseberries 

 at Old Mission, near Traverse Bay. The fruits were covered with its brown 

 felted threads and were rendered nearly or quite worthless as the result of its 

 attack. I am not aware of its occurrence on cultivated gooseberries in this 

 State, but have seen it growing so abundantly upon them in Central New York 

 as to seriously damage the crop. What is believed to be an earlier form of 

 the same fungus is of very frequent occurrence on the leaves of cultivated 

 roses, often proving a great pest in conservatories. The proprietors of the 

 greenhouses in Ann Arbor hold it in check by the prompt application of the 

 flowers of sulphur, a fact that suggests the value of the same remedy for the 

 blights of cherry and apple trees and other plants infested by them. A great 

 number of forest trees and various cultivated trees and shrubs, among them 

 the oak, elm, willow, horse-chestnut, lilac, and others, are attacked by blights, 

 sometimes without apparent injury, though it cannot be doubted that in all 

 cases the growth of these fungi interferes to a greater or less extent with the 

 vital processes of the leaves which they cover and partially choke, besides 

 abstracting their elaborated nutriment. Wherever the disease is limited in the 

 extent of its ravages, as in the case of 'roses or gooseberries and young 

 apple and cherry trees in nurseries, the remedy already suggested will doubtless 

 prove prompt, effectual, and econonomical. 



THE BLACK KNOT. 



To the same general class with the blights, though differing from them 

 greatly in appearance, belong an immense number of fungi, of a hard texture, 

 dark color, and often conspicuous size. Many of these grow upon decaying 

 wood, fallen twigs, dead leaves, and the like, and are of little practical interest 

 except in so far as they perform the office of scavengers, hastening the processes 

 of decomposition and removal of waste material. Some of them, however, attack 

 living plants, and one in particular, very commonly met with in Michigan, is 

 of special interest as being the occasion of the disease of plum and cherry trees 

 known as " black knot." This peculiar excrescence has long been known and 

 by early writers was variously referred to the action of insects, or the combined 



* Pear " blight " does not belong to this class. It will be considered further on. 



