S52 EXPERIMENT STATION RECORD. [Vol. 36 



Sapromyza hispina to determine the possibility of tliese insects serving as car- 

 riers of Bacillus amylovorus. 



From previous experiments (E. S. K., 33, p. 744), togetlier witii the data 

 given in the present paper, tlie authors conclude that practically all insects 

 vi^hich might be important in producing fire blight infections in nurseries have 

 been considered. The various species of flies were not found active agents in 

 increasing the number of fire blight infections, although vi^hen blight is very 

 prevalent and flies numerous, a few infections may be produced by these in- 

 sects. Most of the infection seems to be transmitted through biting or suck- 

 ing bugs. 



Following the observations of Heald (E. S. R., 34, p. 647), the authors in- 

 vestigated the possibility of infection through the water pores of the leaves. 

 From their investigations there is considered to be little, if any, infection 

 through the water pores, injury to the tissue being necessary before the bacteria 

 can produce infection. 



Preliminary studies on the resistance of Prunus to artificial inoculation 

 with Bacterium tumefaciens, C. O. Smith {Phytopathology, 6 {1916), No. 2, 

 pp. 186-19^, pi. 1). — In order to determine more resistant stock on which to 

 graft almonds, peaches, etc., the author has conducted inoculation experiments 

 with about 30 species and varieties of the genus Prunus. 



All the hosts developed typical galls from artificial inoculations except P. 

 pumila, P. ilicifolia, and P. caroUnianc. No varieties of almonds or peaches 

 have been found to show marked resistance, but among the plums it is thought 

 that P. americana and P. hortulana would be well adapted to native species of 

 plums which are not much grown in California. The most popular strains used 

 for grafting were all found very susceptible to crown gall. So far as the in- 

 vestigation has progressed, the author states, no definite recommendation can 

 be made as to the use of resistant stock, although the seedlings of certain Ger- 

 man and Italian prunes should be well adapted as a stock for members of the 

 Domestica group. 



A Porto Rican disease of bananas, G. L. Fawcett {Porto Rico Sta. Rpt. 1915, 

 pp. 36-41, pJ. 1). — A preliminary account is given of a disease of the variety of 

 banana known as Chamaluco. The disease is said to be quite destructive on 

 this variety, and from diseased tissues a species of Fusarium has been isolated 

 Avhich corresponds closely with that described by Ashby (E. S. R., 29, p. 350). 

 Other organisms were found in the tissues, and the author, from his preliminary 

 investigation, is led to believe that the Fusarium is only in part the cause of 

 the trouble. 



For its control, rotation of crops is recommended, and under present condi- 

 tions, the variety Chamaluco can be considered only a temporary crop. 



Citrus canker investigations, W. Newell {Quart. Bui. Plant Bd. Fla., 1 

 {1916), No. 1, pp. 1, 2). — A brief outline is given of the work undertaken by the 

 Florida Plant Board for the eradication of citrus canker in that State. 



Means of identifying citrus canker, R. A. Jehle {Quart. Bui. Plant Bd. 

 Fla., 1 {1916), No. 1, pp. 2-10, pis. 5).— The author gives a list of citrus plants 

 which are subject to citrus canker attack, enumerating them in the order of sus- 

 ceptibility to the disease, after which the characteristics of the disease on the 

 leaves, stems, and fruits of the different hosts are described. 



Sour scab of citrus in Florida, and its prevention, .7. G. Gkossenbacher 

 {Phytopathology, 6 {1916), No. 2, pp. 127-142, figs. ^).— The author describes 

 under the name of sour scab a disease of leaves, twigs, and fruits of certain 

 varieties of citrus which have a strongly acid sap in their growing portions. 



