DISEASES OF PLANTS. 155 



twigs of ypllow biroli. This canker not only causes the disfiguration of tlie 

 tree, but seriously interferes with its growth by cutting off ilie channels of 

 water and reserve transportation. 



An examination showed that tlie canker was due to a si)ecios of Nectria 

 which agrees fairly well with Nectria coccinca, although dittering from the de- 

 scriptions usually given. A modified technical description of the fungus is 

 j)resented. and while there is no experimental proof of its parasitism, it is 

 concluded that the canker of the yellow birch is due to this fungus. The dis- 

 ease is local in its attack, not spreading from a given point of infection Jmt 

 through new inoculations. The point of infection is usually the base of a 

 dead lateral twig, and the cause is proI)ably due to a wound parasite. 



The Novar system of combating larch disease {■lour. Bd. Af/r. [London], 

 12 {1006), \o. 1,2. i)i>- 72.i-725). — On account of the serious injury caused by the 

 larch disease in areas where larch is grown as a pure crop, a number of methods 

 have been suggested for reducing the liability to serious loss. 



A method, known as the Novar system, suggested by Mr. Munro Ferguson, is 

 described which reduces the liability to loss very considerably. This consists 

 of planting pure larch woods, and when the trees attain an age of 10 to 20 

 jears all are removed except the soundest, of which from 300 to 500 per acre 

 are left. Stems that are sound or fairly sound at this age are not likely to 

 suffer from disease later in life. 



In order to keep the surface of the ground clear of grass and similar vegeta- 

 tion, additional trees are provided, and for this purpose it is suggested that 

 Norway spruce, silver fir, or beech be planted underneath the fir, all these 

 species being tolerant to shade. Other species have been experimented with and 

 the list can probably be considerably extended. In about 20 years from the 

 first thinning the larches will be thinned again so as to have a stand of 100 to 

 200 trees per acre, which will be ready for market at from 60 to 80 years. 



Notes on the variation and possible parasitism of Ganoderma sessile, J. B. 

 Pollock (Rpt. Mich. Acad. 8ci., 7 {1905), pp. 53. 5Jf). — A brief account is given 

 ot the occurrence of specimens of this fungus, which were found on a maple 

 tree in the Universit.v of Michigan campus. an<l in addition has been reported 

 on oak trees from other localities. 



The author notes some variations from the original description, and shows 

 that it has stipitate as well as sessile forms. In considering the effect upon 

 the host it is believed to be a wound parasite which destroys the bark and 

 cambium of the tree but does not attack the living wood. 



Bud rot of carnations, F. D. Heald (.1/;.v. /// Hcinu-r. ii. scr.. 2S {1906), No. 

 590, p. 620). — A troul)lesome bud rot of carnations due to a species of Fusarium 

 is described. The rotting buds always contained a mite in addition to the 

 fungus. 



Pure cultures wore made of the fungus, and successful inoculations were 

 carried out. The fungus was again isolated and new inoculations made which 

 indicated that the fungus alone was capa!)le of i)roducing the rotting. The 

 experiment with inoculations of the mite into tlic laids did not produce the 

 disease. It was suggested that the mites act only as carriers of the fungus and 

 intensify its severit.v. The Lawson carnation was noticed as the most suscepti- 

 ble variety. 



A disease of narcissus, F. .7. Chittenden {Gard. Chron., .?. .srr.. 39 {1906), 

 A'o. 1010. p. 277. fi(/. I). — The autlior rei)orts Uh) occurrence in a field of Nar- 

 cissus poeticus of a disease which does not ap])ear to have l)een noticed hereto- 

 fore. Both leaves and fiower stalks were aff(>cted. lait the l)ulbs apjieared not 

 to suffer except in so far as they were injured by intei'ference with the functions 

 of the leaf. 



