DISEASES OF PLANTS. 149 



The barberry and its relation to black rust of grain, H. T. Gussow {Phyto- 

 pathology, 3 (1913), No. 3, pp. 178, 179). — Attention is called to a report on the 

 disappearance of Puccinia graminis in Denmark following the application of 

 the law relating to the destiniction of barberries. 



The action of different luminous radiations on the formation of conidia on 

 Botrytis cinerea, F. ;iik1 Mme. F. Moreau iBuh Hoc. Hot. France, 60 {1913), 

 Xo. 2-3, pp. 80-83). — The authors, studying the development of B. oinerea on 

 carrot under a pure strong spectrum, found that conidia were formed under 

 these circumstances ouly in the violet-blue portion of the spectrum. This result 

 agreed with that obtaiued by Reidemeister (E. S. R., 23, p. 48), but disagreed 

 with that reported by some other authors named. 



A bacterial rot of cucumbers, O. F. Burger {Phytopathology, 3 {1913), No, 

 3, pp. 169, 170). — A brief report is given of two years' investigations of a bac- 

 terial disease of the leaves and fruit of cucumbers. 



On the fruit watery spots with brown centers appear, and later the cucumbers 

 become soft and translucent. The first indication of infection on the leaves is 

 shown by the presence of watery spots. Cultures made from the material 

 showed the presence of a bacterium, and inoculation experiments demonstrated 

 that this organism was the cause of the trouble. 



Vines were reported as drying up without setting fruit, and this led to inocu- 

 lation experiments on healthy flowers. These were found to turn yellow, 

 blacken, and dry up without developing any fruit. 



The cultural characteristics of the organism, which is a species of Pseu- 

 domonas, are being investigated further. 



Corynespora leaf spot of cucumbers, W. Grosser {Illus. Schles. Monatfichr. 

 Obst. Gemuse ii. Gartcnhau, 2 {1913), No. 8, p. 137). — A discussion is given of 

 a disease of cucumbers said to cause great damage in England, but heretofore 

 only sporadic in Germany, and attributed to C. ma;<;ei. 



In the absence of complete investigations as regards efficient and inexpen- 

 sive means of control, the author recommends soaking the seed 4 hours in 0.5 

 per cent formalin solution before planting, also spraying the plant with 0.4 per 

 cent Bordeaux mixture, as preventive measures. No remedy is offered as 

 effective after the general outbreak of the disease. 



Fusarium or Verticillium on okra in North Carolina? G. W. Wilson 

 (Phytopathology, 3 (1913), No. 3, pp. 183-185). — In a previous publication 

 (E. S. R., 26, p. 844), a disease of okra attributed to F. vasinfectum was de- 

 scribed. Later the identity of the fungus had been questioned, and the author 

 reports somewhat more in detail upon the disease and its causal organism. The 

 studies are said to show that the fungus was not a Verticillium but a Fusarium, 

 as previously reported. 



Black heart of potatoes, E. T. Bartholomew (Phytopathology, 3 (1913), No. 

 S, pp. 180-182, pi. 1). — The attention of the department of plant pathology of 

 the Wisconsin Station has been called to a blaclcening of the tissues of potatoes. 

 An examination of these tissues showed them to be sterile. Following this a 

 laboratory experiment was conducted, and it was found possible to produce the 

 condition if potatoes were taken from the storage cellar and exposed to a tem- 

 perature of from 38 to 45° C. (98.4 to 113° F.) for from IS to 48 hours. The 

 blackening did not develop to the same extent in all the potatoes. The change 

 apparently begins in the center and radiates toward the margin, and if the ab- 

 normal potatoes are allowed to remain 10 days or 2 weeks before cutting, the 

 blackened tv^^sues in the center shrink, leaving a hollow with a black lining. 



Further studies are being made on the physiological changes which cause the 

 blackening, and for the present attention is directed to the disease and the im- 

 portance of keeping potatoes at a uniformly low temperature. 



