1018] DISEASES OF PLANTS. 151 



Overwintering of the apple scab fungus, W. P. Fraseb {Science, n. ser., 46 

 (1911), No. 1186, pp. 280-282). — The author reports having observed the apple 

 scab fungus (Venturia incequalis) on young shoots of the apple in the fall of 

 1915. Subsequent to that time, in different sections of Nova Scotia, a number 

 of orchards have been examined where there vpas a severe twig injury due to 

 scab. 



The author is convinced that, at least near the coast, apple scab may over- 

 vpinter on the twigs of susceptible varieties of apple, such as Fameuse and Mc- 

 intosh, occurring as dormant stroma and producing abundant conidia in the 

 spring. Observations made late in the fall indicate that the conidia are more 

 resistant to low temperature than is generally supposed. 



Three cedar rust fung'i, their life histories and the diseases they produce, 

 J. L. Weiheb {Neio York Cornell Sta. Bui. 390 {1917), pp. 507-549, figs. 22).— 

 The author gives an account of investigations of the species of Gymnosporan- 

 gium occurring on cedar, G. junipcri-virginiana;, which has for its alternate 

 host the apple ; G. globosum, which occurs also on quince, pear, and Cratfegus ; 

 and G. clavipes, which attacks in its secial form the quince and Crataegus. 



Inoculations on Ribes with Cronartium ribicola, P. Spauldinq and G. F. 

 Gravatt {Science, n. ser., 46 {1917), No. 1184, PP- 243, 244).— In order to de- 

 termine the possible resistance of species of Ribes to the white pine blister 

 rust, the authors conducted inoculation experiments under controlled condi- 

 tions on 82 varieties of cultivated red, black, and white currants, 23 varieties 

 of cultivated gooseberries, and 42 species and hybrids of Ribes from various 

 parts of the world. 



The varieties of cultivated species of Ribes were found to show considerable 

 variation in their susceptibility to disease. 



In addition to the above species and hybrids, successful inoculations are re- 

 ported on numerous unidentified species of Ribes, including over 100 collections 

 made In the Northwest and Pacific Coast States. Thus far no species has 

 proved to be entirely resistant to the rust. 



[Plant diseases, 1914-15] {Programm u. Jahresher. K. K. Holt. Lehranst. 

 Wein u. Obstbau Klostcrneuhurg, 1914-15, pp. 64-70). — A brief account is given 

 of injury from Peronospora as related to variety and to treatments with Per- 

 ocid, also of chlorosis as influenced by the use of iron salts. 



Plant diseases and control {Programm u. Jahresber. K. K. Hoh. Lehranst. 

 Wein u. Obstbau Klosterneuburg, 1915-16, pp. 76-79, fig. 1). — This is a brief 

 account of variety tests with several proprietary or standard preparations in 

 connection with Peronospora on grapevines. 



The question of curing roncet, E. Pantanelli {Stas. Sper. Agr. Ital., 49 

 {1916), No. 5-6, pp. 249-298). — The author, in continuation of report and dis- 

 cussion regarding studies on the abnormality known as roncet (E. S. R., 28, 

 p. 851), states that this condition tends to persist in shoots from the mother 

 grapevine, although it may show a decrease or apparently disappear in summer 

 with the increased root development. The actual nature and cause of the 

 trouble are still unknown. Material taken from vines affected with this trouble 

 apparently tends to produce vines equally affected. It has not been established 

 that living material from affected plants, if given favorable soil or climate, will 

 recover, hence rigorous avoidance of the use of all such material is recom- 

 mended. 



Dieback, or exanthema, of citrus trees, B. F. Flotd {Florida Sta. Bui. I40 

 {1917), pp. 81, figs. 15). — The author gives a popular summary of information 

 concerning this disease, its cause and treatment. 



Dieback of citrus trees is said to be a disease of the growing tissues, the 

 primary symptoms of which are the formation of gum pockets, the stained 



