DISEASES OF PLANTS. 443 



and a virulent outbreak has reduced the crop by destroying a large portion of 

 the active part of the leaves. 



Angular leaf spot is said to be caused by Bacterium lachrymans n. sp., which 

 enters through the stomata, no wounds being necessary. A technical description 

 of the organism and its morphological and physiological characters are given. 

 It is said to be quite different from that described by Burger (E. S. R., 31, 

 p. 747) in that it does not cause soft rot of the fruit. 



From laboratory tests with copper sulphate the authors conclude that Bor- 

 deaux mixture properly applied would serve to control this disease. 



Investigations on potato diseases (sixth report), G. H. Pethybridge {Dept. 

 Agr. and Tech. Instr. Ireland Jour., 15 (1915), No. 3, pp. Ji91-52G, pis. 12; abs. 

 in Jour. Bd. Agr. [London], 22 {1915), No. 3, pp. 269, 270).— A continuation is 

 reported of the investigations previously noted (E. S. K., 32, p. 239). 



The various comparative trials of proprietary fungicidal preparations made 

 during recent years in Ireland, some of which are described, are said to indi- 

 cate that properly prepared home-made Bordeaux and Burgundy mixtures are 

 preferable to any others tested for use against potato blight {Phijtophthara in- 

 festans), as regards both efficiency and cost. The solutions of 1 per cent strength 

 gave practically as good results as those containing 2 per cent of copper sulphate. 

 Little if any advantage resulted from employment of a potassium instead of a 

 sodium salt in Burgundy mixture for spraying. The source of the blight year 

 after year is regarded as still unsettled. 



Stalk disease (Sclcrotinia sclcrotiorum) was studied, and it appears that 

 lateness of planting confers a degree of protection. The spores appear to be 

 carried by the wind and may cause infection of the aerial parts of weakened 

 or wounded plants at some distance. The yellowing leaves while still attached 

 appear to offer a favorable area for infection by these spores, this fact and the 

 leaf scars probably explaining the prevalence of attack at the nodes. 



The symptoms of pink rot were experimentally produced by inoculation with 

 P. erythroseptica. The cytological work on this fungus begun by Murphy (E. S. 

 R., 83, p. 53) has been concluded, and is to be published in full. 



Corky or pov/dery scab {Spongospora suhterranea) attacked foreign varieties 

 when planted on infected soil in the west of Ireland. Petrol proved inefficient 

 for control of this fungus. 



Studies recently made are considered to prove the identity of the collar fungus 

 (Hypoclinus solani) with that formerly known as Rliizoctonla solani, justifying 

 the rejection of the latter name. 



Comparative experiments with the dry scab or silver scurf fungus (Spondyl- 

 ocladium atro'virciis) suggested that this fungus may attack onlj' while the 

 tuber is still growing, perhaps starting in the dead, exfoliating cells. 



Brown scab is apparently not caused by mechanical irritation, but is due to 

 a widely distributed soil organism, not yet determined, which appears to be 

 sensitive to acids and alkalis. The skin spot, which is provisionally regarded 

 as due to Spicaria solani, is rather infrequent, and apparently of no serious 

 practical importance. 



It is thought, as a result of work not yet completed, that different forms of 

 dry rot exist, but that all are caused by fungi of the genus Fusarium. 



The investigations in connection with the Verticillium disease, which have 

 been continued since 1909, showed during the past season that this disease can 

 be produced in healthy plants by inoculation. 



Leaf roll diseases of the potato, O. Appel (Phytopathology, 5 (1915), No. 3, 

 pp. 139-l.'i8). — In a lecture which was given at a number of universities in this 

 country, the author described some of the diseases of potatoes characterized 

 by curled or rolled leaves, among them curly dwarf, a nonparasitic leaf roll, 



