DISEASES OF PLANTS. 151 



ing liberally applied. Employment of chemical fertilizers with some restric- 

 tion as regards nitrogen is also claimed to prove helpful in producing a freer 

 lineal gi-owth of the shoots favorable to aeration and to the application of 

 sprays. The chief reliance is placed upon copper sulphate as a basis of fungi- 

 cidal treatment. 



Mildew in 1913, A. Cadoret {Prog. Agr. et Vit. (Ed. VEst-Centre), 34 (1913), 

 No. 34, pp. 238, 239).— In continuance of previous reports (E. S. R., 29, p. 551) 

 the author states that, believing both single and successive outbreaks of downy 

 mildew to be favored by humidity, he tested the effects of 3 sprayings following 

 showers or rains extending over several days in the latter part of May and the 

 early part of June. Almost no injury resulted from mildew, while crops around 

 suffered heavily. Similar tests on a neighboring vineyard showed, however, a 

 loss of about 50 per cent, heavy dews being noted in this case. Further tests 

 are contemplated. 



A Botrytis disease of dahlias, M. T. Cook and C. A. Schwarze (Phyto- 

 pathology, 3 (1913), No. 3, pp. 171-174, pi. 1). — During the past year the authors' 

 attention was called to a root rot of dahlias in storage. The disease appeared 

 to be most severe under warm, moist conditions, combined with poor ventilation, 

 and was caused by a species of Botrytis corresponding very closely to the 

 description of B. cincrca. Infections always take place through wounds, and it 

 was imposible to secure the penetration of the fungus through the uninjured 

 epidermis. 



Some fungus diseases of trees, L. H, Pammel (Proc. loiva Acad. Soi., 18 

 (1911), pp. 25-33, p?s. 4, figs. 2). — Descriptions are given of the heart rot of 

 Populus trcmuloides, due to Forties igmarius and F. applanatus ; the oyster 

 fungus (Pleurotus ulmarius) on box elder and basswood; the root rot fungus 

 (Polystictus versicolor) on maples, oak, apple, cherry, and other deciduous 

 trees ; the root rot of oak, due to Armillaria mellea ; the spot of butternut and 

 black walnut (Gnomonia leptostyla) ; and attacks of Taphrina on the Rocky 

 Mountain hard maples. 



Shade tree troubles, G. E. Stone (Massachusetts Sta. Rpt. 1912, pt. 1, pp. 

 73-83, 2J?s. 7). — The author describes staghead and root injury to maple and 

 other trees, injury to cork cambium, sun scald, bleeding, injuries from snow, 

 effect of grading on trees, and injuries from various treatments for protection 

 against insect pests. 



Chestnut blight, G. E. Stone (Massachusetts Sta. Rpt. 1912, pt. 2, pp. 33, 

 34). — A brief account is given of observations by the author on the spread of 

 the chestnut blight and the injury which it is causing. This disease seems to 

 be spreading in the Connecticut and other western valleys of the State, while the 

 eastern central section of the State still remains comparatively free from the 

 disease. Along with the blight there is said to be a deterioration of chestnut 

 trees which is in no way associated with the blight fungus. 



The blights of coniferous nursery stock, C. Hartley (U. S. Dcpt. Agr. Bui. 

 44> PP- 21). — The author describes the more common blights to which coniferous 

 nursery stock is subject and offers suggestions for their control. Among those 

 described are sun scorch, winterkilling, diseases due to parasitic fungi, stem 

 giixlle, mulch injury, red cedar blight, and mechanical root injury. 



Sim scorch, which is said to be the commonest summer trouble, results in the 

 death of the roots before the tops are killed and is due to excessive water loss. 

 Watering, shading, and the avoidance of crowding, as well as increasing the 

 humus content of the soil should be adopted for the prevention of this injury. 



Winterkilling is due to the drying out of the plants when the soil is frozen 

 and may be prevented by the use of a light straw mulch or windbreaks. 



