DISEASES OF PLANTS. 949 



In the 10-year experiments at Geneva. H sprayings witli Bordeaux mixture 

 and Paris green or Bordeaux mixture alone increased tlie yield 73.7 bu. per acre 

 and 3 sprayings increased it 44 bu. notwithstanding tlie fact that the amount 

 of damage done by blight and insects was seemingly small. There was no 

 potato rot found. At Riverhead the gain due to 6 sprayings was 31.25 bu. per 

 acre and to 3 sprayings 18 bu. 



In the cooperative experiments with farmers, which included 152.75 acres, 

 the average gain due to spraying was 36.8 bu. per acre, yielding an average net 

 profit of $17.07 per acre. 



In experiments conducted by 24 volunteers, gains averaging 30.5 bu. per acre 

 are reported. 



Diseased potato seed (Jour. Dcpt. Af/r. West. Aust., 17 (1908), No. 5, p. 857, 

 pi. 1). — A brief note is given reporting the presence in seed potatoes of a 

 disease known as the spindle disease, due to Persola tomentosum. Potatoes 

 affected by this disease put out weak sprouts and their value for seed purposes 

 is greatly reduced. 



The Granville tobacco wilt, E. F. Smith (U. S. Dept. Agr., Bur. Plant Indus. 

 Bid. I'll. pt. 2. pp. 17-2.'i). — Attention was first called to this disease by publi- 

 cations of this Department and also of the North Carolina Station (E. S. R., 

 15, pp. 084. 085), and the author states that the diagnosis given in the North 

 Carolina publication describing the disease and attributing it to bacteria is 

 correct. 



The bacterial origin of the disease is discussed and some recent experiments 

 of the author's described, in which it is demonstrated that the disease is 

 readily coimuunicated to tomatoes through the root system. The cultural 

 characters of the tobacco organism are the same as those of Bacterium solana- 

 cearuui derived from tomato or potato, and there is no doubt but that the 

 Granville wilt of tobacco and the brown rot of the potato, tomato, and egg- 

 plant are all due to the same organism. In the case of tobacco it seems prob- 

 able that the main infection takes place through the root system. A very con- 

 siderable extent of the destructive prevalence of the disease seems to be 

 coincident with the abundant occurrence of root nematodes. 



For the control of the disease, planting tobacco only on uninfected land, 

 reducing the amount of infectious material as much as possible, avoiding the 

 wounding of roots in transplanting, and breeding resistant varieties as far as 

 possible are among the measures recommended. 



The black rot of grapes, I>. Ravaz {Ann. Sci. Agron., 3. ser., 3 (1908), II, 

 No. 2, pp. 179-182). — This is a iiaper presented before the International Con- 

 gress of Agriculture held at Vienna in 1907, in which the author gives an ac- 

 count of the black rot of grapes and discusses means for its control. 



In France, it is said, the fungus has rather definite periods or cycles of ap- 

 pearance during the season. For its prevention vines should be sprayed with 

 some of the fungicides containing copper comi)ounds at intervals of 8 to 10 

 days (huing the early part of the season. Later applications are to be made 

 whenever spots caused by the fungus are noticed on vines left unsprayed to 

 serve as indicat<»rs of the presence of the disease. 



The control of the gray rot of grapes, G. Istvanffi (Ann. t!ci. Agron., 3. scr., 

 3 (1908), II, No. 2, pp. 196-230).— An account is given of studies on the control 

 of the gray rot of grapes due to the fungus Botrj/tls ciiurcd. the conidial phase 

 of Sclrrotinid fuvkeUnnn. The method of attack, development and liiolojiy of the 

 fungus, varietal resistance of grapes to attack, etc., are described, after which 

 the treatment by means of powders, liquid fungicides, etc., are discussed. 



