DISEASES OF PLANTS. 447 



had four years previously borne a crop of white clover while the other bore 

 red clover, the former showed good stauds in the spring while in the latter the 

 clover had practically all died out. It is stated that after vigorous growth 

 begins in the spring the danger of spread and further injury by canker is 

 probably small, and it is thought advisable to plant Italian rye grass in the 

 killed areas. A top-dressing of potash, phosphoric acid, and liquid manures is 

 also recommended. 



In spite of the mild winter, it is said that sufficient snow lay on the ground 

 to produce a considerable Fusarium attack on rye. Treatment of the seed 

 with corrosive sublimate is favored. 



Appearance of clover canker, K. Stoemeb (Dcut. Landw. Presse, 40 (1913), 

 No. 29, pp. 350, 351). — The author discusses a severe outbreak of clover canker 

 in several parts of the Province of Pomerania, due to Sclerotinia trifoliorum. 

 The fungus is said to present a certain simihirity to that seen in ergot of rye. 

 No reliable means of control is yet offered. The use of chemical fertilizers, 

 foreign species of clover, or alternation with Italian rye grass, etc., is recom- 

 mended. 



The rice crop failure in the residency of Madion in 1910, P. van der Elst 

 (Dept. Landh., Nijv. en Handel [Dutch East Indies], Meded. I'roefstat. Rijst., 

 1912, pp. IV-\-10Ji, pi. 1, figs. 2). — This is a study of the rice disease long known 

 on certain flat lands of Madion, locally called omo mentek and thought to be 

 identical with that called brusone in Italy, imoci in Japan, ufra in India, and 

 rust in the United States. 



The disease is said to begin with the death of the root hairs and to proceed 

 upward, killing and rotting the rootlets to levels near the surface of the 

 ground. It is associated with continued flooding or protracted rains (as dur- 

 ing the east monsoon) ; with poor drainage and aeration; with oxygen starva- 

 tion of the roots, due to the presence of reducing substances and a compact 

 structure of the soil ; with the presence of weeds ; and with the previous plant- 

 ing of sugar cane on the same soil, resulting in lack of nitrogen or phosphoric 

 acid, or both. The author suggests rice root rot as the most appropriate and 

 descriptive name for the disease. 



Preventive or remedial measures recommended include the improvement of 

 the soil structure by addition of organic manures, by drainage, and if neces- 

 sary by turning it temporarily to meadow; the better regulation of the rota- 

 tion where sugar cane is involved; a more careful selection of seed; the early 

 drainage and ventilation of the soil after the setting in of the east monsoon; 

 the proper timing of the planting with regard to monsoon changes ; dry seed 

 beds ; cultivation of the. ground before the setting in of the west monsoon ; 

 planting in drills ; regulation of water supply during cultivation ; adaptation of 

 artificial manures; proper control of weeds; and alternate cultivation of the 

 soil with ample irrigation, avoiding stagnation of the water. 



Septoria pisi in relation to pea blight, I? E. Melhus (Phytopathology. 3 

 (1913), No. 1, pp. 51-58, pi. 1). — An investigation was begun in 1911 of S. pisi 

 in relation to pea blight. A number of authoi-s have reported Ascochyta pisi 

 as causing injury to peas, but the author's observations indicated that this 

 fungus was not present in any quantity and that S. p-isi was associated with 

 the disease in great abundance. Infection experiments were carried on which 

 showed that most of the trouble was due to 8. pisi. 



While carrying on these studies the possibility of the connection of Myco- 

 sphverella pinodes with S. pisi was considered. It seems that Mycosphserella is 

 associated with Ascochyta rather than Septoria. There is believed to be 

 evidence indicating a perfect stage of the fungus 8. pisi, but as yet it has 

 not been discovered. 



