. DISEASES OP PLANTS. 449 



cankers and inoculation experiments have shown tlie identity of the fungus, so 

 that it seems certain that the same species produces l)lotclies on the fruit, 

 canliers on tlie twigs, and spots on the leaves. 



In connection with spraying experiments for the control of orchard diseases, 

 the authors have found that apple blotch can be readily prevented by thorough 

 spraying with Bordeaux mixture. As the fungus winters over in the cankers 

 on the twigs, it is believed that by thorough spraying for to'O or three years, 

 it could be practically eliminated. 



The gummosis of the Amygdalacese, A. Rant (Inaufi. Dis.s-., Amsterdam, 

 1906; abs. in Ztschr. Pflanzeitkrank., 11 {1901), No. 3, pp. 119, 180).— The 

 author gives a review of the theories of gum formation, after which he descril)es 

 the anatomical changes associafed with it. He claims that a distinction should 

 be made between tlie gum that is formed within the cells and that in the inter- 

 cellular spaces. Only the intercellular formation of gum gives rise to the 

 phenomena associated with the disease known as gummosis. 



The formation of gum in the intercellular spaces is said to be due to the de- 

 velopment of new tissues, the lignification of tissues, and the activity of 

 wounded cells. The activity of the wounded cells is often caused by attacks of 

 bacteria, fungi, and boring insects. Among the more common fungi are 

 ClaMcrosporium carpophilum and Coryneum, heijerinckii. Cytnspora leucos- 

 toma, or Valsa Icucostoma, is less important but causes the peculiar gummosis 

 of cherry trees that is characterized by the accumulation of gum under the 

 bark. Species of Monilia also cause gummosis of various stone-fruit trees, and 

 Botrytis ciucrca produces the disease on cherry trees. Bacteria are also said 

 to cause this disease. 



Concerning' the origin of the gum on cherry trees, K. Mikosch (Sitzber. 

 K. Akud. ir/.s-.s-. [Vienna], Math. Naturic. KL, 115 (1906), No. 6, pp. 911-961, 

 jjls. .'/). — A discussion is given of the origin of the gum that accompanies the 

 disease of cherries known as gummosis. This gum is considered a pathological 

 product and follows wounds of the cambium, its formation taking place within 

 the inner jxtrtions of the cambium layer. 



A peach disease {Gard. Chron., 3. ser., J,2 (1901), No. 1018, p. 160, fig. 1).— 

 A disease of peaclies due to Hehninthosporium rhaJdiferum is briefly described. 

 This fungus, which causes a black moldy ai»pearance of the ripened fruit, was 

 first observed and described by Berkeley in 1S(i4, but it appears not to have been 

 recognized since that time. Although the fungus is rare, from the nature of its 

 attack it would probably prove a decided pest if abundant. 



The writer recommends the picking and burning of diseased fruits and spray- 

 ing the trees with dilute Bordeaux mixture whei'e the disease is present. 



Diseases of strawberries {Osterr. Gart. Ztg., 2 (1901), No. 9. pp. 311-320).— 

 A summary is given of fungus and insect injuries to the strawberry. For the 

 prevention of the various root diseases, the author reconmiends the sterilization 

 of the soil where the plants are to be set with a weak solution of formaldehyde. 

 To combat the attacks of Ramularia, Phyllosticta, and Ascochyta on the leaves 

 the use of a 1 iier cent Bordeaux mixture is advised. For the false or downy 

 mildew spraying with Bordeaux mixture or ammoniacal copper carbonate is 

 considered advantageous. For the prevention of powdery mildew, sulphur 

 should l)e dusted over the plants or they should be sprayed with a fresh sohi- 

 tion of potassium suliihid. 



Studies on the development of GlcBOsporium ribis, the means of infection, 

 and the methods for combating it, R. Ewekt (Ztschr. Pflanzenkrank., 11 

 (1901), No. 3, pp. 158-169, pis. 2). — A description is given of the development of 

 G. ribis, or Pseudopeziza ribis, together with the results of exi)eriments on its 

 means of infection and methods for preventing its attack upon currants. 



