1142 EXPERIMENT STATION EECOED. 



that they can not be successfully segregated as species, as they were unable to 

 find differences other than the host plant of sufficient constancy or importance 

 to distinguish the species or even varieties. On this account the authors are 

 for the pi'esent disposed to regard the various forms as varieties of one species, 

 and for reasons presented they refer them all to GloinercUa rufomaculans, 

 which was originally described from specimens from the grape. A brief account 

 of these investigations has been given elsewhere (E. S. R.. 18. p 94^). 



An account of the genus Pythium and some Chytridiaceae, E. .J. Butler 

 {Mem. Dept. Agr. India, Bot. Sei:. I {1!)07), No. 5, pp. 161, pis. 10). — A mono- 

 graphic study is given of the genus Pythium, in which the biology, phylogeny, 

 and systematic relations are described. Most of the species are said to be 

 saprophytic, although some have become hemisaprophytie, causing destructive 

 plant diseases. In thrs respect they resemble parasites, although their best 

 development occurs when living as saprophytes. 



Observations are given on some Chytridiaceae which are parasitic on aquatic 

 Saprolegniaceje, etc., and a number of new species of the different genera ai'e 

 described. 



Diseases of fruit and fruit-bearing plants {London: Bd. Agr. and Fisheries, 

 191)6, pp. 13, charts 7). — A series of colored charts with explanatory text illus- 

 trating and describing the gross characters of a number of the more prevalent 

 fungus diseases of fruits and fruit-bearing plants, and giving suggestions for 

 their control or eradication. The charts are intended for hanging in school 

 or lecture rooms, and the diseases illustrated are strawberry leaf-spot, straw- 

 berry mildew, apple rot, cherry scab, apple mildew, apple canker, heart-wood 

 rot, tree-root rot, bladder plums, peach leaf-curl, shot-hole fungus, leaf blight, 

 apple scab, pear scab, brown rot, vine leaf-blotch, vine leaf-scorch, black rot 

 of vine, powdery mildew of vine, pear leaf cluster-cups, apricot rust. American 

 gooseberry disease, walnut leaf-blotch, cherry leaf-blotch, hazel mildew, and 

 silver leaf. 



The scab of apples and pears, E. Voces {Dciif. Laiidir. Pressc, 3-'/ {1907), 

 Nos. 33, pp. 216, 211 ; 3'/, pp. 2S-i, 285; 3:>, pp. 290, 291, figs, i?).— An account is 

 given of the biology of the species of Fusicladium that cause the scab of apples, 

 pears, and cherries. The organisms are described at length and the methods by 

 which they gain entrance to the host plant, the effect produced on the hosts, the 

 methods of propagation of the fungi, and the susceptibility of varieties to infec- 

 tion are all treated at some length. 



The perennial mycelium of pear rust, K. von Tubeuf {Xaturic. Ztschr. 

 Land u. ForsUv., 5 {1901), No. 4, pp. 211-219, fig. i).— The author figures and 

 describes the appearance of the necidial stage of pear rust on shoots of trees 

 where the mycelium nuist have been perennial, as the time of occurrence and 

 location seem to indicate that it had wintered on the host plant. 



Oidium or powdery mildew of the vine, F. T. Bioletti {California i^ta. Bid. 

 1S6, pp. 315-3-')2, fi(fs. 11). — A description is given of the Oidium or powdery 

 mildew of the vine, which is due to the sunmier or conidial phase of Unciniila 

 spiralis. This disease, according to the author, is one of the most serious 

 fungus diseases to which grapes in California are subject. 



After describing the fungus and its effect upon the host plant, the author 

 gives accounts of the methods of treatment, the application of sulphur, it is 

 claimed, being the most efficient. Methods of training, cultivation, and irri- 

 gation which keep the vine dry minimize the danger of attack. The weather 

 and season when the sulphur is api)lied are of great importance, and the number 

 of treatments will vary with the locality, season, and variety. The cost of 

 the sulphur and its application will vary from 50 cts. to .$2.2.i per acre, depend- 

 ing upon the form of apparatus and the fineness of the sulphur. Thus far 



