DISEASES OF PLANTS. 455 



Cyperus rotundus, J. Welbohn ( Texas Farm and Ranch, 16 (1897), No. 37, p. J). — 

 A. popular description of this weed. 



On the destruction of -weeds (Prog. Agr. ei Vit., 28 | 1897), No. 31, j>i>. 138, 139). 



On the destruction of Juncus and G'arex in meadows, J. Graftiau | Iikj. Agr. 

 Gemblotu; 1S97, No. 0). 



DISEASES OF PLANTS. 



Apple rust, F. I). Chester i Delaware Sta. Bpt. 1896, pp. 63-69, figs. 

 5). — JsTotes are given on various species of Gymnosporangium and the 

 relation between the different stages of this fungus as produced on 

 cedar and apple trees is pointed out. The species of apple rust occur- 

 ring in the United States are enumerated. Of these species Gymno- 

 gporangmm macropus, G. globosum, and G. clavipes are the most injurious 

 to the cultivated apple, having lor their teleutospore host the red cedar. 

 The destruction of such trees in the immediate vicinity of apple orchards 

 is recommended. Notes are given which seem to indicate a marked 

 variation in susceptibility of the different varieties of apples to the rust, 

 and a tabulation is presented of the varieties of apple trees occurring 

 in 3 different orchards with the relative amount of rust infection on 

 each variety. 



Pea blight, J. H. PANTON (Ontario Agr. Col. and Expt. Farm Ept. 

 1890, pp. 13-15). — Notes are given of a diseased condition of pea vines in 

 which the affected plant fades and appears prematurely ripe while the 

 peas are scarcely formed in the pod. Such vines appeared in patches 

 over the field, but soon spread, covering large areas. On close exam, 

 ination, the plants are seen to be decayed at the surface of the ground 

 and in some cases mycelial films were present. Examinations for Per- 

 onospora vieicv and Erysiphe martii faded to show either of these fungi 

 present, nor were any insect attacks noticed. The author is inclined 

 to believe that the blight in question is a diseased condition of the 

 plant due to adverse physical conditions of the soil, extreme drought, 

 and the continual planting of tVe peas on the same ground year after 

 year. 



The spotting of peaches, F. I). Chester (Delaware Ma. Bpt. 1896, 

 pp. (a i-63, Jigs. J). — This disease, which is due to Gladosporium carpo- 

 philum, is one of the most common in the State. It is characterized by 

 the appearance of small black spots ^ to £ in. in diameter, more or 

 less congregated or united. When the spots coalesce over a consider- 

 able portion of the fruit, uniform black blotches occur where the skin 

 becomes tough, dry, and leathery. The disease affects the fruit by 

 reducing the market value, on account of rendering it unsightly in 

 appearance, and by causing the fruit to crack, offering easy entrance to 

 other organisms which produce rapid decay. It also greatly reduces 

 the size of the infected fruit. Notes are given on the life history of 

 the fungus and on successful inoculation experiments on plums made 

 with spores taken from pure cultures. When the spores were placed 



