846 EXPERIMENT STATION EECOED. 



The control of damping'-off disease in plant beds, J. Johnson (Wisconsin 

 Sia. Research Bui. 31 (1914), PP- 29-61, p/.s. 2, figs. 7). — An Investigation is 

 reported on the cause of damping-off of seedlings in plant beds and methods for 

 the control of this trouble. In Wisconsin the disease is commonly caused by 

 I'ythium deTjaryanum and a species of Rhizoctonia, These fungi attack a large 

 yjiriety of plants and their development is favored by excessive moisture and 

 high temperatures. 



For preventing attacks of these fungi a number of chemical agents have been 

 tested, among them formalin, copper sulphate, ammoniuih copper carbonate, 

 copper acetate, copper nitrate, Bordeaux mixture, lime sulphur mixture, potas- 

 sium sulphid, sulphuric acid, potassium permanganate, mercuric chlorid, potas- 

 sium nitrate, and iron sulphate. Of the chemicals tested a solution of formalin 

 1 part to 50 of water at the rate of 2 qt. per square foot of soil will prevent 

 damping-off under the most favorable conditions for fungus growth. It was 

 also found somewhat beneficial in stimulating plant growth and killing weed 

 seeds. Sterilization of soil by heat gave the most satisfactory results and the 

 inverted pan method is recommended where facilities are at hand for its appli- 

 cation. Attention is called to the secondary effects of soil sterilization in that 

 weed seeds and insect pests are killed and the vigor of plant growth is stimu- 

 lated. 



As a cultural means of control of this disease, growers are recommended 

 to avoid infected, poorly drained soils and thick sowing of seed. Where the 

 disease is present the covers of the plant beds should be removed so as to 

 reduce the temperature and moisture of the soil as well as that of the air in 

 contact with the plants. A list of the literature cited is appended. 



The relation of Fusarium. nivale to Nectria graminicola, J. Weese (Ztschr. 

 Gdnmpsphysiol., 2 {1913), No. 4, pp. 290-302) .—B.ei)Ovtmg a study of F. nivale, 

 claimed by Ihssen (E. S. R., 23, p. 545) to be a stage of X. graminicola, the 

 author states that these two fungi are not identical. 



A study of some imperfect fungi isolated from wheat, oat, and barley- 

 plants, E. C. Johnson (17. S. Dept. Agr., Jour. Agr. Research, 1 (1914), No. 6, 

 pp. 475-490, pis. 2). — Attention is called to the fact that many imperfect fungi 

 are parasitic on cereals wherever climatic conditions favor their development. 

 A study was made of some of these fungi occurring on wheat, oats, and 

 barley, and pure cultures were obtained of Fusarium culmorum, Ilclmintho- 

 sporivm gramincum, Cladosporium gramineum, and a species of Alternaria, 

 and after profuse sporulation had been induced tests were made of their patho- 

 genicity on the leaves, seeds, and seedlings of wheat, oats, barley, and rye. 



Inoculation experiments in the greenhouse showed that certain species greatly 

 reduced the germination and development of the plants. The root develop- 

 ment of wheat plants attached by Helminthosporium was stunted and the roots 

 were markedly inferior to those developed on plants grown from clean seed. 

 An experiment on soil infection showed that this was a possible means by which 

 the Helminthosporium attacked the cereal, and the experiment indicated that 

 the soil remained infected for at least two months, during which the experiment 

 was in progress. Field experiments with these fungi substantiated the results 

 obtained in the greenhouse, although the reduction in germination and injury 

 to seedlings was somewhat less in the field experiments. 



The author concludes from his experiments that E. gramineum and F. cul- 

 morum were parasitic, while C. gramincum and the undetermined species of 

 Alternaria were not parasitic under the conditions of his investigations. 



A brief bibliography is given. 



The culture of cereal rusts in the greenhouse, F. D. Fromme [Bui. Torrey 

 Bot. Club, 40 (1913), No. 9, pp. 501-521). — The author describes experiments by 



