DISEASES OF PLANTS. 551 



Diseases of the prickly pear, H. Tryon (Queensland Agr. Jour., 27 {1911), 

 No. 2, pp. 76-80). — A list is presented of different fungi tliat liave been reported 

 uix)n prickly pears (Opuntia spp.), and suggestions are given regarding the 

 possibility of some of them being utilized in destroying prickly pears in 

 Australia. 



The chestnut bark disease, F. W. Rane (Boston: State Forester, 1912, pp. 

 10, pis. 4, niap 1). — An account is given of the history and distribution in 

 Massachusetts of the chestnut bark disease, due to Diaporthe parasitica. The 

 author states that the disease is almost universally distributed through the 

 State, infection in the western half being quite general. On account of the 

 severe infection and the small proportion of chestnut timber that could be 

 saved, he thinks the State would not be justified in- making any attempt to 

 eradicate the disease. 



The fate of the chestnut tree, H. Hitier (Rev. Hort. [Paris], 8^ (1912), 

 No. 1, pp. 17, 18). — Attention is called to the severe losses in Fi-ance and else- 

 where due to the black canker of chestnut trees, the author stating that fully 

 10,000 hectares of plantations of this species have been devastated. 



He points out that Mangin attributes the disease to the presence of a para- 

 site, Mycelophugus castanece. This destroys the mycorrhiza and young roots of 

 the trees, diminishing the absorbing surface of the plants. 



It has been ^ggfested that grafting chestnuts upon oaks might give favorable 

 results, as well as the use for stock of the Japanese chestnut, which so far has 

 proved resistant. 



Notes on the oak Oidium. in France, G. Aenaud and E. Foisx (Compt. Rend. 

 Acad. Sci. [Paris], 154 (1912), No. S, pp. 124-127).— Aceording to the authors, 

 perithecia of the fungus which occurs so abundantly in the oidium stage on the 

 oak in France and other parts of Europe were found on the leaves of Quercus 

 sessiliflora in December, 1911. The presence of these fruiting organs made it 

 possible to determine definitely the relationship of the conidial with the perfect 

 stage. 



Studies of material and comparisons with specimens received from America, 

 where the fungus has long been known, led the authors to decide that it be- 

 longs to Miorospli(era quercitm. M. aim of some authors is held to be a 

 synonym of the first mentioned species, the name of which is preferred. 



Notes are given on the distribution of the fungus in France and some of its 

 most prominent characters. It is stated that while the Oidium on the oak has 

 long been known, it is only recently that the perithecia have been recognized. 



Expert opinion on dry rot, C. Wehmer (Jahresber. Ver. Angeio. Bot., 8 

 (1910), pp. 178-198). — This is an account of the examination, microscopical 

 and cultural, of certain woods and other structural materials from buildings 

 alleged to be attacked by dry rot, with the opinions of botanists on the cases. 



Three fungi werf identified, viz, MeruUus lacnjmans (true dry rot), Condo- 

 phora cerebella, and Polyporus xaporm-ius, of which characteristic appearances 

 are briefly given. Other species may have been present in one instance. Cul- 

 tures were not very successful. Recommendations are made as to prevention 

 of attacks and treatment of infected woods. 



A disease of sweet peas, asters, and other plants, G. Massee (Roy. Bot. 

 Card. Kew, Bui. Misc. Inform., 1912, No. 1, pp. H-52, pi. 1). — The author de- 

 scribes a disease attacking asters, sweet peas, and various other cultivated 

 plants, especially during their seedling stages, by a stage of the fungus Thie- 

 lavia Tiasicola. The form of the fungus described is that called Miloivia nivea, 

 from its abundant white mold-like growth. 



The symptoms of disease in different plants are described, and the treatment 

 of seed beds by sterilizing with formaldehyde or by heating is advised. Where 



