DISEASES OP PLANTS. 249 



309). — In continuation of the author's investigations on the soo*^y mold of 

 tobacco (E. S. R., 25, p. 455), a study was made of the effect of temperature 

 on the formation of honeydew on the plants. Strong healthy plants about 

 one-third grown were subjected to low and high temperatures by watering 

 with hot and cold water, by placing ice around the plants, by injecting steam 

 under bell jars, etc. 



Aside from the temporary disturbance to the nutrition and transpiration of 

 the plants, no injurious effect was noted, and it is concluded that sudden 

 inequalities of temperature have no direct relation to the secretion of honeydew. 



Some means for the control of Thielavia on tobacco, Aielli-Donnarumma 

 (Bol. Tec. Coltiv. Tahacchi [Scafati], 10 (1911), No. 5, pp. 211-281; abs. in 

 Intemat. Inst. Agr. [Rome], Bui. Bun Agr. Intel, and Plant Diseases, 3 (1912), 

 No. 1, pp. 310, 311). — In experiments in the hybridization of tobacco it has 

 been found that some crosses between the varieties locally known as Ken- 

 tucky and Italia are quite resistant to attacks of T. basicola. One form, 

 called type B, is not only of excellent character as to growth, productivity, 

 and quality, but out of 60 plantations containing more than 320,000 plants, 

 none was attacked by the fungus. 



Diseases of cabbage and related crops and their control, L. L. Harter ( U. 8. 

 Dept. Agr., Farmers' Bui. 488, pp. 32, figs. 1). — Popular descriptions are given 

 of a number of the more important diseases of cabbage and other cruciferous 

 plants, with directions for their control. The diseases described are club 

 root, nematode root knot, black rot, wilt, blackleg, soft rot, malnutrition, downy 

 mildew, white rust, spot disease of cauliflower, leaf blight, powdery mildew and 

 damping off. 



Tomato leaf rust {Bd. Agr. and Fisheries [London], Leaflet 262, 1912, pp. 3, 

 fig. 1). — A description is given of the leaf rust of tomatoes due to Clados- 

 porium fulvum, which, it is said, is becoming a serious pest in parts of Europe. 

 Spraying, if attempted, should be begun early so as to protect the plants, and 

 when the plants are young half-strength Bordeaux mixture may be employed. 

 When the plants are in flower and young fruit present, the use of a solution 

 of potassium sulphid is recommended. 



The enzymatic activity of some fruit fungi, D. Bruschi (Atti. R. Accad. 

 Lincei Rend. CI. Sci. Fis., Mat. e Nat., 5. ser., 21 (1912), I, Nos. 3, pp. 225-230; 

 4, pp. 29S-304). — ^After a brief account of observations made by others in 

 this connection, the author reports his own studies with Fusarium niveum, 

 F. Igcopersici, and Monilia cinerea, in substance as follows : 



The toxic activity of the 3 fungi studied upon the cells of such fruits as 

 are attacked by them, as the plum, tomato, etc., is not proportional to the 

 acidity of the fungus extract employed, and this toxicity is decreased by 

 heating. None of these 3 fungi produces an enzym capable of attacking 

 cellulose, but F. niveum and M. cinerea secrete a pectinase which, by dis- 

 solving the middle part of the cell wall of fruits, produces rapid maceration. 

 It is doubtful if this ability is shared by F. lycopersici. Each of these 3 fungi 

 appears to develop an enzym capable of breaking up nitrogen compounds into 

 proteids and nonproteids. 



Gummosis, F. A. Wolf (Plant World, 15 (1912), No. 3, pp. 60-66.).— The 

 author reviews the various theories that have been advanced to explain the 

 phenomenon of gummosis, which is conspicuous in species of Pruuus and 

 . Citrus. He claims that until the immediate cause of gummosis is demon- 

 strated, it is reasonable to believe that enzyms play a very important role. 



Apple tree anthracnose, H. S. .Tackson (Oregon Sta. Circ. 11, pp. 4). — The 

 apple tree anthracnose due to Oloeosporium malicorticis is described. This is 

 one of the most serious fungus diseases of the apple in Oregon. It causes 



