DISEASES OF PLANTS. 649 



of the strains was found parasitic on apple leaves, but they were found to 

 follow Sph(cropf<:is malorum as saprophytes or facultative parasites. 



Twig blig'ht and blossom blight of the apple, J. L. Hewitt {Arkansas Sta. 

 Bui. 113, pp. J/93-505). — In this bulletin the author aims to present the results 

 of about three years' investigation on the twig blight and blossom blight of the 

 apple in such form as to make them available for popular use. 



The cause of the disease, Bacillus amylovorus, is said to attack several 

 species of plants, causing twig blights. On the apple it causes five types of 

 injury — body canker, fire blight, twig blight, blossom blight, and collar blight. 

 The disease is spread, particularly in case of infection of blossoms and twigs, 

 by various insects. Attention is called to the resistance of different varieties 

 and individual trees to attack. Chemical examinations of specimens of twigs 

 and fruit spurs showed that there was a rather definite relation between the 

 starch content, as shown by analyses, and the susceptibility to blight. 



In a subsequent bulletin the author expects to give more detailed statements 

 of the experiments that have led up to the present popular summary. 



An unknown apple tree disease, J. L. Hewitt and H. E. Truax {Arkansas 

 Hia. Bui. 112, pp. J/Sl-^Ol, figs. IJi). — A description is given of a disease of apple 

 trees which at first was thought to be of fungus origin. The disease first ap- 

 pears as scattered red pycnidia-like pustules on the young, smooth bark. These 

 average about 0.5 mm. in diameter and about half as much in height. As the 

 disease progresses the pustules become more numerous until the limb is covered, 

 making the bark very rough. If a thin portion of the phelloderm is cut from 

 the older areas the remaining cut surface will be seen to be spotted with 

 numerous dark spots on the former site of the pustules. 



Another form of the disease, called the scurfy type, is characterized by an 

 irregular thickening of the phelloderm for a considerable area on the branches. 

 This area is darkened in color, often becoming dark red or nearly black. 



A characteristic condition which seems to be associated with this disease is 

 the lack of leaves on the infested limbs. So far, however, there are but few 

 instances where the trouble seems to have been the definite cause of the death 

 of the trees. Examinations up to the present time have shown no organism 

 which could be definitely considered as the cause of this trouble. The authors 

 expect to continue their investigation as to the cause and means of control of 

 this disease. 



The greening of wood of pear trees, P. Vuillemin {Compt. Rend. Acad. Sci. 

 [Paris], 157 (1913), No. 5, pp. 323, 32^).— Attention is called to the greening of 

 the wood of pear trees by the fungus Hclotiuvi wruginescens found on many 

 specimens in Lower Normandy. This fungus had been previously reported 

 occurring on the oak and beech, and also on birches, but has not hitherto been 

 recognized as occurring on the pear tree. Its abundance on pears is held to be 

 an indication of a weakness of the trees rather than the presence of a parasite. 

 The greening, it is said, is often called green rot, but the designation is consid- 

 ered to be an improper one, as the wood remains solid and preserves its condi- 

 tion indefinitely, although retaining its unusual color. 



Cronartium ribicola and the proscription of Ribes nigrum, F. C. Stewart 

 and W. H. Rankin (Ahs. in Phytopathologij, 3 {1913), No. 1, p. 73),— The 

 authors report a severe outbreak of Cronartium on currants at Geneva, N. Y., 

 in 1912. The black currant seems to be especially sub.iect to attack by this 

 fungus, and it is thought that its planting should be discouraged. See also a 

 previous note (E. S. R., 29, p. 249). 



Diseased gooseberry bushes, A. Steffen {Prakt. Ratgeber Obst u. Oartenbau, 

 1912, p. 183; abs. in Mijcol. Centbl, 2 {1913), No. S, p. 172). —The author gives 

 the results of his study of the American gooseberry mildew fungus, which ia 



