648 EXPERIMENT STATION RECORD. 



Insect control important in checking fire blight, A. C. Bubkill {Phyto- 

 patlwlogif, 5 (1915), Xo. 6, pp. 343-347). — As a result of observations and ex- 

 periments, the author claims that the control of aphids and leaf hoppers, which 

 are carriers of blight, would prove cheaper than the present method of prun- 

 ing, which is not only expensive but only partially effective. It is specifically 

 stated, however, that this does not apply to the elimination of hold-over cankers, 

 a subject which still needs investigation. 



Fire blight on cherries, J. W. Hotson {Phytopathology, 5 (1915), Xo. 6, pp. 

 312-316, pi. 1). — The author reports serious damage done by fire blight (Bacil- 

 lus amylovorvs) in the Yakima Valley in 1914 and 1915 on apples and pears, 

 as well as on quince, prune, and crab. During the spring and early summer of 

 1915. it is said that there was a noticeable increase in the infected pears and 

 apples on trees showing little twig or body infestion. About the middle of 

 June, when the cherries were beginning to ripen, a peculiar condition of the 

 fruit on Royal Ann cherry trees was observed, in which about one-third of 

 the fruit on a large tree was infected. 



The cherry disease first appears as small depressions on the sui'face of the 

 fruit. These gradually spread over the entire surface, giving the cherry a 

 shrunken, wilted appearance. In some instances, exudations were noticed on 

 the fruit, and examination showed the exudate contained abundant bacteria 

 which cultures and inoculation experiments proved to be identical with 

 B. amylovofous of the pear and apple. 



While on the cherry bacteria, so far as reportetl, occur only on the fruit, 

 the author considers it possible that under favorable conditions the organism 

 may acquire increased pathogenicity and attack this host as it does the pear 

 and apple. 



A contribution to our knowledge of silver-leaf disease, J. SmolAk (Ann. 

 Appl. Biol, 2 (1<U5), No. 2-3, pp. 13S-157, figs. 20).-— This is mainly a cytolog- 

 ical study describing the departures from the normal cell conditions which 

 were observed in silvered leaves of Primus domcstica. The author states that 

 the facts as described show clearly that the alterations displayed by such leaves 

 are not confined to the development of air spaces and the separation of cells, 

 but are far more profound than was at first supposed. 



A review of comparisons of healthy with abnormal tissue led to the con- 

 clusion that the latter behaves as if parasitized. On structural grounds, it 

 apparently belongs to the category of gall-tissue, taking the term gall in its 

 larger sense. 



It is considered possible that certain bacteria occasionally found in plum 

 leaves showing the disease may be related thereto in some way, and are hence 

 a proper subject for further study in this coimection. 



A bil)liograi)liy is appended. 



On diseases of plum trees caused by some species of Cytospora, W. N. C. 

 Belgrave (Ann. Appl. Biol, 2 (1915), No. 2-3, pp. 183-19^, figs. 10).— The 

 author has described a disease of plum trees as probably due to one or more 

 species of Cytospora, the fungus isolated in most cases being closely related to 

 or identical with C. Ic'ucostoma. 



Complete germination of the spores occurred only in the presence of organic 

 nitrogen. Pyciiidia and spoi-es resembling those occurring naturally were 

 obtained in artificial culture, but attempts to induce formation of perithecia 

 were unsuccessful. 



Mildew on black currants, V. B. Stewart (Phytopathology, 5 (1915), No. 6, 

 p. 3Jf9). — The author reports a block of black currant nursery stock which was 

 noticed in July, 1915, as badly affected with niildow (Spharothcca mors-uvcc). 

 In the nursery, all the varieties of black currant and several adjoining rows of 



