150 EXPERIMENT STATION EECORD. 



rust to distinguish it from another rust that is said to b9 of nonparasitic 

 nature, is characterized by the occurrence of spots on the leaves, surrounded by 

 a darli green border, indicating the extension of the diseased tissue. Usually 

 the disease appears only in tobacco fields at higher elevations, although in wet 

 seasons it occurs also on the lower estates. The cause of the disease is said to 

 be Bacterium pseiulozoogloece n. sp. A technical description of the bacterium is 

 given and its cultural relations are described. The bacterium is said to be not 

 strictly parasitic, but becomes so under special conditions, among which humid- 

 ity is the most important. 



A brief bibliography is appended. 



The effect of dust from cement m^ills on the setting of fruit, P. J. Anderson 

 {Plant World, 11 (1914), A'o- 3, pp. 57-68). — This is an account of investigations 

 carried on by the author, a preliminary note of which has appeared elsewhere 

 (E. S. R., 27, p. 152). 



Summarizing the results of the investigations, the author states that dust 

 from cement kiln stacks containing a large amount of alkaline, soluble calcium 

 salts was found to settle on vegetation within a radius of 2 miles from the 

 mills. When the dust falls on fruit blossoms some of it goes into solution in 

 the stigmatic secretions and pollen falling on the stigma will not germinate and 

 the flowers are not fertilized. Artificial tests show that pollen will not germi- 

 nate in even very weak solutions of the dust. When blossoms of apple and 

 other fruits were dusted as fast as they opened, only a very small proportion 

 .set fruit. 



Fruit culture in Normandy, J. Porter (Jour. Bd. Agr. [London], 20 {1914), 

 No. 10, pp. 860-865, figs. 2). — Along with other information the author notes 

 that black scab, the chief fungus pest of pears at the present time, may be pre- 

 vented by frequent spraying with soda Bordeaux or Burgundy mixture during 

 the year. In winter, however, he finds it cheaper and apparently as effective to 

 use a 7 per cent solution of iron suli)hate in place of the soda Bordeaux. 



A rust new on apples, pears, and other pome fruits, P. J. O'Gara (Science, 

 n. ser., 39 {1914), No. 1008, pp. 620, 621).— A description is given of a rust 

 due to yEcidiHin hlasdaleawum, the telial stage of which is said to be Gymnos- 

 porangimn hlasdaleanum, parasitic on the incense cedar of the Pacific coast. 

 The disease was first noticed in 1908 and has since been under observation. It 

 is said to occur rather sparingly on apples, but attacks certain varieties of 

 pears very seriously. The rust is not roestelia-like, as in the case of the com- 

 mon apple rust. Its host plants, so far as known, include apple, crab apple, 

 various pears, mountain ash, quince, serviceberry, and thorn apple. 



Experiments with apple leaf spot fung'i, J. W. Roberts {U. S. Dept. Agr., 

 Jour. Agr. Research, 2 {1914), No. 1, pp. 57-66, pi. 1).—A study was made of 

 certain leaf spot fungi to determine whether they were capable of enlarging 

 spots already formed. 



In these experiments inoculations were made both in the greenhouse and 

 orchard on unsterilized leaves, by spraying spores on leaves which contained 

 dead spots made by touching them with the heated end of a steel rod. It was 

 found that under certain conditions Altcrnaria mall was able to enlarge the 

 dead spots on the apple leaves, from which it is concluded that this species is 

 a rather strong facultative parasite. Goniothirrium pirinitm was found to pos- 

 sess but little power of enlarging dead areas and, according to the author, may 

 therefore be classified as a saprophyte or at least as a weak facultative parasite. 

 Coryneum foliicolum, Phyllosticta Umitata, Monot-luactia malt, and Phomopsis mali 

 are, so far as the apple leaf is concerned, believed" to be purely saprophytic, 



A technical description of A. mali n. sp. is given. 



