376 PATHOLOGY [Bot. Absts. 



2573. Blan chard, E., and C. Perret. Recherches relatives a la maladie de l'enroule- 

 ment de la pomme de terre effectuees dans le departement de la Loire. [Experiments on leaf 

 roll of potatoes in Loire.] Ann. Serv. Epiph. 5:245-252. PI. 1. 1918. — Leaf roll has appeared 

 in Loire and adjoining provinces and probably has existed there since 1909. Early varieties 

 like Early rose, l'lnstitut de Beauvais, Merveille d'Amerique, and Franco-Russe are espe- 

 cially susceptible but Richter Imperator, a mid-season variety, has not proved resistant. 

 Violette d'Auvergne appears to possess resistance but is susceptible to rot. — Andrea and Fluck 

 geante are also resistant. — Richter Imperator (susceptible), when free from leaf roll yielded 

 4,500 kilos more per hectare than Violette du Farez (resistant), but under disease conditions 

 yielded 4,300 kilos less. — The use of stable manure or of nitrate of soda reduces the loss from 

 leaf roll. — Disinfection experiments indicate that if leaf roll is caused by an organism, the 

 germ does not persist in the soil or on the surface of the tuber. — D. Reddick. 



2574. Blan chard, E., and Claude Perret. Sur l'enroulement des feuilles de la pomme 

 de terre. [Potato leaf roll.] Compt. Rend. Acad. Agric. France 5: 356-358. 1919.— The re- 

 sults of experiments continuing for several years lead to the belief that nitrogen hunger is 

 the chief symptom of the disease. It is considered a degenerative disease which is brought 

 about by continued asexual reproduction, too frequent planting on the same soil, deficiency 

 in potash, etc. It is ameliorated by abundant fertilization with sodium nitrate, although this 

 is not a cure, at least in the first year. All varieties tested were found subject to the disease, 

 but not to an equal degree. In even the most susceptible varieties, some individuals proved 

 entirely immune. — E. A. Bessey. 



2575. Boas. [Weihenstephan.] [Rev. of : Bohm, Fr. Die zuchterische Bekampfung der 

 Blattrollkrankheit der Kartoffeln. (Control, through breeding, of the leafroll disease of pota- 

 toes.) Illustr. Landw. Zeitg. 37: 341-342. 1917.] Zeitschr. Pflanzenkrankh. 29: 54. 1919. 

 — Author, from his experiences, states that the hereditary, infectious leafroll disease is to 

 be distinguished from the non-hereditary through the paler color of the leaves. The cause 

 of the hereditary trouble is held to be due to a species of Fusarium. Dry warm weather favors 

 the development of the disease. The paper reviews other work done on this trouble to gain 

 a clear meaning of the leafroll diseases. Author refers finally to the question of deteriora- 

 tion, quoting as an example a variety of potato, which he has studied since the seventies of 

 last century. The variety is now so badly deteriorated, that one finds it difficult to secure 

 the necessary quantity of seed potatoes. — H. T. Giissow. 



2576. Bratjn, Harrt. Presoaking as a means of preventing seed injury due to disinfect- 

 ants and of increasing germicidal efficiency. Science 49: 544-545. 1919.— In the course of 

 investigations on the bacterial black-chaff disease of wheat, a new method of seed treatment 

 has been discovered which practically eliminates seed injury due to the use of disinfectants, 

 and at the same time renders pathogenes on the seed coats more susceptible to the action of 

 the disinfectant. The seeds are allowed to absorb water for a definite period in advance of 

 treatment. The saturation of the cells and the cell walls with water before treatment, and 

 the dilution of the full -strength disinfectant beyond the point of injury as it enters the tissues, 

 in accordance with the law of diffusion of dissolved substances, is the explanation of the re- 

 sults obtained. According to this method, infected seeds are soaked in water for ten minutes, 

 then drained and kept moist for six hours. They are then soaked for ten minutes in formalin 

 1 : 400 solution, drained, and covered for 6 hours. They are then dried over night and planted 

 next day. If copper sulphate is used, presoaked seeds are thoroughly wetted in the 1 : 80 

 solution, drained and kept moist 20 minutes, plunged for a moment into milk of lime, dried 

 over night and planted. Nino different varieties of wheat, also oats, barley and maize have 

 been treated successfully by this method. — A. H. Chivers. 



2577. Brick, C. Bericht iiber die Tatigkeit der Abteilung fur Pflanzenschutz fur die 

 Zeit vom 1 Juli, 1916, bis 30 Juni, 1917. [Work of the division for plant protection, 1916-1917.] 

 Jahrb. Hamburger wiss. Anst. 1918: 16. 1918. — Gooseberry mildew (Sphaerotheca mors-nvae) 



