154 EXPERIMENT STATION EECORD. 



seription of the honey fungus {Armillaria mellea) (E. S. R., 24, p. 45) is given 

 and of the appearance of potato tubers which are attaclied by it. 



The tubers are more or less enveloped by chocolate-colored, branching rhizo- 

 morphs of the fungus, which form white sheets of mycelia in the tissues of the 

 potato. Ultimately the whole tuber is destroyed and shrivels into a dry mass 

 similar to the dry rot produced by the fungus Fusarium soJani. 



Investigations on the leaf-roll disease of the potato, G. Bohutinsky- 

 Keizevci (Ztschr. Landw. Versuchsic. Osterr., 13 (1910), No. 7, pp. 607-633, figs. 

 3). — ^As a result of further investigations (E. S. R., 23, p. 743) on the leaf-roll 

 disease of the potato, the author claims that the disease is carried over from 

 one year to the next on the potato skins, although plants, the tubers of which 

 are sound, may undoubtedly be infected by means of wind-carried spores. 



The infection originates in the growing points of roots and shoots, where the 

 fungus attacks principally the tenderest tissues, usually the root hairs in the 

 case of the roots. By the destruction of the root hairs the larger rootlets are 

 weakened or even killed, while invading saprophytes continue the work of de- 

 composition even into the stems. The injurious effect of the fungus attack 

 manifests itself principally, especially under unfavorable conditions, in a check- 

 ing of the growth of the plant. 



Judging from the fruiting stages, the fungus seems to be a pyrenomycete 

 with a Helminthosporium fructification. The infection of sound tubers can 

 occur by means of the tubers of diseased plants. Much more active, however, 

 in this respect are the shoots and roots of such tubers. 



Treatment of the tubers of diseased plants with formalin proved worthless in 

 controlling the disease, 



[Experiments on the leaf-roll disease of the potato], O. Reitmaib {Ztschr. 

 Landw. Versuchsw. Osterr., 13 (I'JIO), No. //, /*/). 190-197). — In a report on the 

 work done by the agricultural-chemical experiment station at Vienna for the 

 year 1909, the results are given of field experiments on inheritance and the 

 physical condition of the soil as factors in the development of the leaf-roll dis- 

 ease of the potato. 



It is claimed that the disease can be produced by using tubers from diseased 

 plants, and can be transmitted from generation to generation of potatoes with- 

 out the intervention of fungi. 



The intensity of the disease was found to be decidedly affected by external 

 growth conditions in some cases, even entirely disappearing under favorable 

 soil and weather environments, while mechanical conditions of the soil unfavor- 

 able to the vigorous growth of the potatoes clearly increased the intensity of 

 the disease. If such conditions are continued for a few years, they will finally 

 result in the complete destruction of the crop. 



The leaf-roll disease of the potato, its cause and prevention, J. Vanha 

 (Monatsh. Laiidtv., 3 {1910), No. 9, pp. 268-276, figs. 2).— As a result of obser- 

 vations and inoculation experiments the author claims that the principal cause 

 of the leaf-roll disease of the potato is, in the cases investigated, an ascomy- 

 cetous fungus belonging to an undescribed genus and si^ecies, for which the 

 name Solanella rosea n. g. and n. sp. is suggested and a technical description 

 of which is given. 



The fungus exists in the soil, on the surface of which its ascomata are borne, 

 and is disseminated by means of the tubers. A similar disease is also produced 

 by a nematode, which the author provisionally calls Tylenchus I. 



Lohsol (from 20 to 40 cc. to every square meter of soil), a carbolineum prepa- 

 ration, was found very effective against the disease, either when mixed with 

 the soil or when used for disinfecting the seed tubers. 



