748 EXPERIMENT STATION RECORD. 



the first time in 1908, followed in 1909 by serious outbreaks. Under natural 

 forest conditions Quercus cciTis is more resistant to the disease. than Q. pednn- 

 cvlata and Q. sessiliflora, while Q. rubra is extremely resistant, as are all the 

 cultivated American species, even when in the same gardens with native Euro- 

 pean oaks which are severely attacked by the mildew. 



In some cases the smaller twigs and branches were killed by the attack, 

 in addition to a general lowering of the vitality of the tree due to leaf fall. 

 The disease is attributed to O'idiiim quercinvm gemmiparum. 



A bibliography is appended. 



On outbreaks of oak mildews, P. Magnus (Yereinsschr. Gesell. Luxemi. 

 Naturfr., 1910, pp. 108-111; abs. in Centbl. Bakt. [etc.], 2. Abt., 29 {1911), No. 

 4-5, p. llJf). — It is claimed that the mildew epidemic on the European oaks in 

 1907 was caused by a Microsphsera, probably M. quercina, while the mildew 

 in western France on Quercus tozza was probably a form of M. aim, which 

 developed only the Oi'dium fructifications on the European oak. 



Willov/ trees killed by Armillaria mellea, F. T. Brooks {Gard. Chroti., 3. 

 ser., 49 (1911), No. 1260, pp. 100, iOi).— Attention is called to the occurrence 

 of this fungus on the roots of a species of willow (Salix alba), causing the 

 sudden death of many of the trees. In England the fungus is rarely found on 

 dicotyls, but is often very destructive to conifers. Ash trees which have been 

 pltinted among the willows seem to be immune to the disease, and the replace- 

 ment of the willows by ash is therefore recommended. 



The diseases and enemies of roses, R. Laubert and M. Schwartz {Roscth- 

 lirankheiten vnd Eosenfeinde. Jena, 1910, pp. VI-\-59, pi. 1). — Under this title 

 the authors list and discuss the principal diseases and insect enemies of the 

 rose, including directions for the control of each. 



Notes on the free-living' nematodes, F. A. Potts {Quart. Jour. Micros. Set. 

 [London], n. scr., 55 (1910), No. 219, pp. Ji3S-J,S-',, figs. 11; abs. in Zeiitbl. Allg. 

 n. Expt. Biol., 1 {1910), No. 15-16, pp. 563, 564 ) -—Biological studies are 

 reported. 



ECONOMIC ZOOLOGY— ENTOMOLOGY. 



The farmer's interest in g'ame protection, E. H. Forbush {Agr. of Mass., 

 57 {1909), pp. 273-279).— The author briefly considers the value of game birds 

 and mammals, the financial benefits derived from game, and its artificial 

 propagation. 



Plague amoung ground squirrels in America, G. W. McCoy {Jour. Hyg. 

 [Cambridge]. 10 {1910), No. 4, pp. 589-601, />?s. 2, nmp 1).—A table accompany- 

 ing this brief summarized account shows the number and results of examina- 

 tions made of ground squirrels collected in 25 counties in California. A map 

 gives the area from which examinations of squirrels have been made, and the 

 approximate location of infected points. 



An outbreak of rat plague in SufEolk, A. M. N. Pringle {Pub. Health [Lon- 

 don], 24 (1911), No. 4, pp. 126-131).— This is a detailed account of the occur- 

 rence of plague in England as previously noted (E. S. R., 24, p. 556). 



It has now been conclusively shown that over a large area of a part of East 

 Suffolk rats are at the present time dying of acute plague. " In addition hares 

 Lave been found to have died of the disease in the same districts. IMany dead 

 rabbits have been found, but up to the present plague has been found in only 

 one case, the other rabbit deaths being due to other diseases which investigation 

 would show to be common at this period of the year in any case. One cat has 

 also been found infected and several ferrets. . . . Apart from the rats the 

 infection of other animals must be regarded as an accidental concomitant of the 

 rat epizootic." 



