268 STATE HORTICULTURAL SOCIETY. 



action of these and some fungus growth. The first to give a complete descrip- 

 tion of tlie knot and the fungus by which it is caused was Dr. W. G. Farlow, 

 Professor of Cryptogamic Botany in Harvard University. The admirable 

 account of tlie disease given by this author is too extended for anything more 

 than a brief reference. Its destructive influence is shown by the fact that in 

 many localities in the Northern States plum trees have been completely ruined 

 by it, ■vfhile " in some parts of New England, particularly in Maine, and along 

 the sea-coast, the raising of cherries has been almost abandoned in consequence 

 of the ravages of the black knot." In ^Michigan it is most frequently met with 

 on cultivated plum trees. At Ann Arbor it is abundant on wild plum trees 

 and near Grand Haven specimens were noticed in the summer of 1882 growing 

 on the choke cherry. I am not aware of its occurring with us on any other 

 trees. Its propagation is secured by the production of several kinds of spores, 

 one sort being jiroduced from spring to the latter part of summer on exposed 

 parts of the knot where they can be carried away readily by the wind or birds 

 or by other agencies. The perfect resting-spores (with some others whose sub- 

 sequent history is less known) reach maturity in the middle of winter, ready to 

 be disseminated in like manner when the knot becomes hollow and broken, as 

 is the case with old specimens. 



The occurrence and method of reproduction of the black knot suggest (1), 

 That when it has attacked a cultivated plum or cherry tree, the only remedy 

 is to cut away altogether the limbs upon which it is growing and burn them ; 

 (2), That the wild plum and the choke cherry upon which the knot grows are 

 a nuisance and ought to be exterminated in order to prevent the spread of the 

 disease from them to cultivated trees. The removal of the wild plum trees 

 covered with knots that are now standing half a mile below Ann Arbor near 

 the left bank of the river, certainly comes within the authority of our officials, 

 and might properly receive their attention. Doubtless our worthy Secretary 

 has already noticed the knots that are growing luxuriantly on the plum trees 

 on his new place, and will take care of them as soon as he gets settled. 



MUSHROOMS AND TOADSTOOLS— DRY ROT. 



The large class to which the more conspicuous fleshy fungi belong, such as 

 the " mushrooms"' and "toadstools," derives its chief economical interest from 

 the edible properties of some of its species and the poisonous nature of others. 

 Still there are at least two species? that from their connection with the disease 

 known as ''dry rot" in timber, deserve special mention here. These two are 

 named respectively ■nierulius lachrymans and 2^oliji)orus liyhridas. Like other 

 fungi they grow besi when their surroundings are warm and moist, and accord- 

 ingly are of more frequent occurrence in the moist climate of the British 

 islands than in the United States. Still the dry rot is by no means unknown 

 in this country. A few years ago Mr. E. L. Jenney, then Professor of Archi- 

 tecture in the University of Micliigan, brought to Ann Arbor specimens of 

 wood from some of the large beams in the Portland block in Chicago that were 

 entirely ruined by the dry rot. The fragments which he brought were of a dull 

 brownish color, looking some as though they had been subjected to the action 

 of intense heat and crumbled beneath the touch. Microscopic examination 

 showed the fine white filaments of the fungus that was the occasion of its dis- 

 eased condition ramifying through the substance of the wood. Without goiog 

 into complete details, it may be stated that the great cause of dry rot, whether 

 in oak or pine, is imperfect seasoning and exposure to a damp atmosphere. If 

 it were possible to thoroughly season all timber employed in building, and then 



