DISEASES OF PLANTS. 749 



to 12 in, tall. Plants thus treated are held in a moist atmosphere at 20 to 25° 

 C. (68 to 77° F.) over night and removed the following morning. 



It is believed that by this method it will be possible to learn the relative 

 resistance of any variety of potato without growing it under held conditions. 



Production of tobacco varieties resistant to slime bacteria, J. A. Honing 

 (Mcclcd. Dcli-Procfstnt. MviJan, S (1913), AV>. /, pp, J2-21).—In a preliminary 

 report of further work (E. S. li., 2S, p. 44G), the author states that of 87 

 selected varielies of tobacco from Java, Cuba, Mexico, the United States, Brazil, 

 Paraguay, Dominicau Republic, the Philippines, Japan, and Hawaii all proved 

 to be susceptible to Bacillus solanacearum, showing bacterial gummosis. Some 

 Deli varieties were somewhat less affected, as appeared to be also two from 

 the Philippines and one from Japan. These are discussed as a possible source 

 for the development of more resistant varieties. 



Tomato leaf spot, H. C. Long (Gard. Chron., 3. ser., 5/f {1913), No. 1^07, pp. 

 Jfl7, 418, fig. 1). — Reviewing briefly the history of Septoria lycopersici, causing 

 leaf spot of tomatoes in England since 1907, the author approves the remedial 

 measures recommended by Giissow (E. S. R., 20, p. 346). 



A new disease of tomatoes, P. Vogland (Ann. R. Accad. Agr. Torino, 55 

 (1912), pp. 379-SSl) .—The author describes Cladosporimn fulvum vioUiceum, a 

 new variety parasitic on tomato leaves. It is differentiated from the tji)ical 

 species mainly by the violet colored mycelium and conidiophores, characters 

 which were maintained in cultures of the fungus. 



Diseases of pear and apple trees, P. Passy (Jour. Soc. Nat. Ilort. France, 

 J,, ser., IJf (1913), Dec, pp. 7S1, 7S2).—To a brief discussion of the pear disease 

 the author adds a description of water core in apples, the glassy portions 

 showing early attack by worms. 



Treatment of chlorosis in fruit trees, G. RiviiiRE and G. Bailhache (Jour. 

 »S'oc. Nat. Hort. France, 4. ser., 14 (1913), May, pp. 287, 288).— It is stated that 

 besides supporting conclusions from experiments previously noted (E. S. R., 27, 

 p. 48), this study, carried out with apple and pear trees, seems to show that 

 the favorable results observed in connection with use of iron sulphate are at- 

 tributable to the metallic component of this salt, and not to the sulphuric acid. 



Restoration of color to etiolated plants, L. Godde (Jour. Soc. Nat. Ilort. 

 France, 4. ser., I4 (1913), May, pp. 290, 291). — Discussing some disadvantages 

 ascribed to use of iron sulphate for chlorosis of fruit trees, etc., the author 

 recommends a formula employing potassium sulphate, iron filings, and copper 

 chips in the projjortion of 76 : 6 : 1. 



Fungus gummosis, H. S. Favvcett (Cal. Cult., 42 (1914), No. 4, pp. 99-102).— 

 Including under the term gummosis all gumming formations and exudations of a 

 somewhat permanent character, whether due to unfavorable climatic conditions 

 or to parasitic invasion, the author discusses some work of other investigators 

 on stone fruit and citrus trees, also some of his own relating more particularly 

 to the latter. 



It is stated that a bacterium (Pseudomonas cerasus) is at least partially 

 responsible for cherry gummosis, which it is said may be largely prevented 

 by budding in the limbs of Mazzard cherries as stocks, or limited by cut- 

 ting out and disinfecting diseased areas. Apricot gumming receives much the 

 same general tro:itment. At least five kinds of gum diseases of citrus trees are 

 knowu in California (2 of which are ascribed to fungi), some account of these 

 being given with treatments adapted to particular form.s. The brown rot gum- 

 mosis is ascribed to Pythiacystis citropJithora and the gray rot gummosis to 

 Botryiis vulgaris. 



