Pflanzenkrankheiten. 341 



Roberts, J. W., Experiment with apple leaf-spot fungi. 

 ijourn. Agr. Res. II. 57—66. pl. 7. April 15, 1914.) 



Alternavia Mali is considered a rather strong facultative para- 

 site; Couiothyrmm piriniini is barely accorded rank as a facultative 

 parasite; and Corynetim. folicolwn, Phyllosticta limitata, Monochaetia 

 Mali and Phomopsis Mali are held to be purely saprophytic, so far 

 as concerns apple leaves. Trelease. 



Roberts, J. W., Sources ofthe early infections of apple 

 bitter-rot. (Journ. Agr. Res. IV. p. 59—64. pl. 7. Apr. 15. 1915.) 



Glomerella cingidata, in addition to passing the winter in rotted 

 apples and in the cankers which it causes on the tree, is shown 

 to winter over in cankers and dead parts of the apple tree due to 

 orher causes than the attacks of this fungus. Trelease. 



Spaulding, P., The damping-off of coniferous seedlin^s. 

 (Phytopathology. IV. p. 73-88. 1914.) 



In conciusion the author states that the damping-off of conifers 

 is, caused by several widely-different fungi and occurs under such 

 different conditions in different places that no rule of treatment can 

 be devised which will apply generally. An intelligent study must 

 be made of each locality, before any Statement can be made asto 

 the best culture methods to be used for the prevention of damping- 

 off in that locality. 



The experimental work seems to lead to the following conclu- 

 sions: Soil sterilization sufficient to prevent damping-off is effectively 

 accomplished with formalin (preferably 1 ounce to 1 gallon of water, 

 or stronger with a suitable interval before seeding), sulphuric acid 

 (1 ounce to 1 gallon of water or stronger), and ammonium copper 

 carbonate (rather dilute). No chemical is perfectly effective in stop- 

 ping outbreaks of damping-off when applied after germination, sul- 

 phuric acid probably being best under most conditions. Weak formalin 

 applied after germination is worse than useless. The fungi causing 

 damping-off are so different in their characters and modes of attack 

 that methods of treatment and chemicals to be used will vary 

 according to the fungus found to be causing the disease. 



The seed used undoubtedly has much to do with damping-oft". 

 Observations show that seeds which are light-weight and poorly 

 filled, such as are usually obtained in years of scarcit5^ produce 

 weak seedlings which are longer in germinating and which are very 

 subject to this disease. A specific instance may be mentioned: seeds 

 of Pi)nis sylvestris in the spring of 1908 were very high-priced and 

 of poor quality, while those of P. strobus were cheap and of ver}^ 

 good quality. The damping-off attacked only the former. In 1907 

 conditions were exactly reversed, and so was the damping-off on 

 the seedlings in the same nurseries. M. J. Sirks (Haarlem). 



Stewart, A., Som. e observations on the anatomy and 

 other features of the "black knot". (Amer. Journ. Bot. I. 

 p. 112—126. pl. 9-10. Mar. 1914.) 



Referring to Plowvightia galls on Prunus. Trelease. 



