DISEASES OF PLANTS. 1047 



The most injury is said to be due to attacks of C. pini and C. cfrrulea. The 

 mycelium of the fungi was found to be able to attack and destroy the living 

 tissues of conifers, growing much more rapidly in moist than in dry timber. 

 The specific gravity and strength of timber was found to be decidedly reduced, 

 due to the presence of the fungus. 



A fir disease in Saxony, F. W. Neger (Tharand. Forstl. Jahrh., 58 {1908), 

 \o. 2, pp. 201-225, pis. J, figs. 2). — For a number of years the fir trees of Saxony 

 and other parts of (iermany have been sub.ie<'t to a disease which the authoi 

 was commissioned in l!t05 to study and report upon. 



The disease is manifested upon the trees in the thinning of the leaves and 

 the dying of the branches, the top of the tree being usually first to show the 

 trouble, and by a water-soaked appearance of the heart wood. An investiga- 

 tion showed that the disease was due to Agaricus mclleus attacking the trees 

 through their taproots. No parasite of any kind was found on the leaves or 

 in the injured twigs. The mycelium of the mushroom forms a dense network 

 of rhizomorphs about the taproot and later enters the tissues, finally causing 

 a rotting of the roots. Later the horizontal roots are invaded and the tree dies. 



The attack of the fungus is favored by anything that weakens the vitality 

 of the tree, such as smelter fumes, checking the transpiration stream, resulting 

 in a water-logged condition of the stem and main roots, lack of light, etc. 

 Correcting these conditions will to a great degree diminish the spread and 

 injury due to the parasite. 



The white-pine blight in Maine, W. J. Morse (Rpt. Forest Comr. Maine, 

 7 (li)07-S), pp. 20-25, pi. 1). — On account of the recent interest in the blight 

 of white pine, the author was led to investigate during the past summer the 

 injury to white pine in a number of localities in Maine. He found that there 

 is no connection between the so-called white-pine blight and that recently de- 

 scribed in a pamphlet of the Forest Service of this Department ( E. S. R., 20, 

 p. 549). Practically all of the so-called pine blight in Maine in 1907 and 1908 

 is believed to have been due to adverse weather conditions duriug the past two 

 winters. 



The infectious chlorosis of the Japanese euonynius, E. Baur (Ber. Deut. 

 Bot. (JescU.. 26a (1908), No. 9, pp. 711-713). — In continuation of [trevious exper- 

 iments (E. S. R., 18, p. 648), the author has made a study of the chlorotic forms 

 of the Japanese euonymus and of variegated forms of privet. In some cases he 

 has been able to transfer the infection by means of inoculation experiments, 

 while in others he failed. On this account he is led to the conclusion that there 

 maj- be an infectious and a noninfectious form of chlorosi.s. In a previous re- 

 port he stated his belief that the infectious virus could be isolated, but thus 

 far he has failed to do so. 



The destruction of wood by fungi, A. H. R. Buller (Set. Prog. Twentieth 

 Cent., 3 {1909), Xo. 11, pp. 361-378, figs. 3).— A discussion is given of the de- 

 struction of wood by fungi and attention called to a number of the more com- 

 mon species of fungi that attack structural timber, decaying trees, etc. 



North American rose rusts, J. C. Arthur {Torreija, 9 {1909), A'o. 2, pp. 21-28, 

 fgs. 3). — AccDrding to the auth<)r practically ail rose rusts in North America 

 have been hitherto i)laced under two" si)ecies, Phnigmidium speeiosum and 

 /'. siibeortieiiini. Subsei|nent studies, however, have shown that liiere are a 

 iiuml)er of distinct species, and are recognized, all of which are indigent)us 

 but one. The distribution of these species throughout the United States is 

 indicated. The spec-ies recognized are /'. umerivuniini, I', rosw-sctigerw, P. 

 rosw-californiecc, P. roscr-arkanisana; P. montivagum, and P. disciflorum. 



