DISEASES OK PLANTS. 1()(')1 



developed ami iKtrnial, and w Idle no structural changes are observed in the stems, 

 branches, or leaves, these organs are of a pale yellow color and quite deficient 

 in chlorophyll. There are certain modifications produced in the flower that arc also 

 mentioned. A iHind)er of causes are discussed, such as nematode worms, root lice, 

 fungi, bacteria, varieties, effect of transplanting, heredity, property of soil, etc., 

 from which it has l)een di'ternuned that none of these can V)e definitely ascribed as 

 the cause of the disease. It seems that it is due to an obscure derangement of the 

 vital fiincticms of the plant. Brief notes are given on the aster rust, and attacks of 

 beetles, grassh()pi)ers, etc. 



Iieptosphseria vagabunda and Pleospora negundinis, i'. A. J. A. Oi:i)emans 

 {Proc. Sec. Sci. Koninkl. Akad. Wetemrh. AmMerdam, 3 {1901), pp. 141-151, pi. 1). — 

 Descriptions are given of these fungi which cause diseases of trees, the first species 

 occurring on Knden and the second on Negundo. The Leptosph;eria causes small 

 oval black spots 0.5 to 1.5 cm. long on the surface of the young branches. The 

 infection takes place through the lenticels, and as the dead tissue is cut off by a 

 cork layer it is comparatively harmless. Associate<l with it was found a new species 

 of Phoma, to which the name P. tili:r is given. It is believed to be a form in the 

 life cycle of the fungus. Experiments are reported in which a number of black 

 spots were cut from the bark, crushed, and thoroughly macerated with distilled 

 water, after which the mass was filtered through a Chamljerland-Pasteur filter, and 

 young shoots of healthy trees were treated with the filtrate by inoculation and by 

 immersion. The l)ranches changed to a reddish-brown color within a few days, 

 while others treated in a similar manner with distilled water remained green. The 

 disease of Negundo seems to be confined to nursery stock under 3 years old, and 

 causes much injury. Diseased branches show discolored areas somewhat resembling 

 those descril)e<l a1)(>ve as occurring on the linden. In this case the infei'tion is appar- 

 ently through v.'ounds, often at the base of the leaves. An enzym is associated with 

 this fungus as in the former case, and is believed to be the principal cause of the 

 injury. In both diseases the inycelia are the sources of injury, and from both 

 of them the enzym has been separated. The mycelial filaments of the Tilia disease 

 are colorless, devoid of partitions, and very thin and delicate; while those occurring 

 in the disease of Negundos were brownish in color, septate, and occurred in consider- 

 able masses. The enzym of the Tilia disease acts locally; that of the Negundo may 

 give rise to infections at considerable distance from the point of inoculation. 



A disease of birch trees, R. Paulson {Essex Nat., 11 {1900), p. 273, figs. 8; 

 abs. in Jour. Roy. Hurt. Soc. \_London'\, 26 {1901), No. 1, p. s-^^'j).— This disease, which 

 is reported in Epping forestand elsewhere, completely destroys many of the trees. The 

 disease is attributed to the fungus Meldnrorns hiUistoma. Hitherto this fungus has been 

 considered to be a saprophyte, attacking only dead tissues, but the conclusion is 

 arrived at that it occurs on the living branches, causing their death; however, as a 

 rule, its perfect form is only found on dead branches. The course of the disease is 

 said to be rapid. 



Pestalozzia hartigii in Ariege {Rev. Eaux et Forets, 40 {1901), No. 17, pp. 537- 

 S39). — The occurrence of this fungus upon young beech seedlings is reported, and it 

 is thought to be the first record of its occurrence in France. The fungus attacked 

 the young trees in the nursery, causing a reddish-l)rown discoloration at tlie collar of 

 the plant. The most seriiMis injury was done in nurseries situated at an elevation of 

 about 1,350 meters. It is reported to have destroyed at least 80 i)er tent of seedlings 

 in some localities. 



The leaf-cast disease of pine, E. Ebermayek {Allg. Forsl u. .hujd Ztg., 07 

 {1901), Sejil., pp. .W9-.il4). — A review is given of the various theories relative to the 

 cause of leaf casting of pine trees, ])articular attention being given to the theories of 

 excessive evaporation, frost injury, and attacks of the fungus LopJiodermium pinastri. 



13U2— No. 11—02 5 



