DISEASES OF PLANTS. 1059 



black or greenish black, and are surrounded by light brown rings. 

 The boundary line between the healthy and diseased tissue is conspicu- 

 ously marked. The tissues within are blackened to a considerable 

 distance below the surface and tbere is somewhat less than the normal 

 amount of moisture present. There are no indications that either the 

 stem or the leaves are attacked by the disease. Old specimens often 

 show species of Fusarium, Peuicillium, and various bacteria, but 

 attempts made to cultivate in Petri dishes an organism from the dis- 

 eased tissue developed nothing. If any organism is connected with 

 this disease, it is one which does not readily grow in agar. 



Investigations concerning potato scab, Frank and Kruger 

 (Ztschr. Spiritusind., 19 (1896), Erganzungsheft, pp. 9, pi. 1 ; abs. in Bot. 

 Gentbl., 73 (1898), No. 9, pp. 327, 328).— The authors have made a study 

 of the various forms of potato scab and some of the means for their 

 prevention. 



It is claimed that Spongospora solani, a rather common north European 

 fungus, was not a constant accompaniment ot the disease. Bolley's 

 potato scab bacterium was not observed in any specimens. Thaxter's 

 fungus, Oospora scabies, was found abundantly. The authors are some- 

 what inclined to think the micro organisms play a secondary role in the 

 disease, the primary cause probably being some soil or other condition 

 rendering the tuber susceptible of infection. Marling alone is "said not 

 to be the cause of this probable soil condition and the exact role played 

 by marl is to be investigated further. 



As preventive treatment the authors recommend soaking seed tubers 

 in a 2 per cent Bordeaux mixture before planting. 



A lily bulb disease, G. A. Massee (Kew Misc. Bui. 122-123, pp. 

 87-90, pi. 1). — This disease, brief mention of which has been given else- 

 where (E. S. R., 9, p. 457 , is caused by a parasitic fungus, Rhizopus 

 necans, illustrated descriptions of which are here given.. It was first 

 noticed on bulbs of Lilium speciosum and L. auratum from Japan. The 

 fungus grows readily as a saprophyte in quite a number of culture 

 media, fruiting in five or six days. 



Culture experiments indicate that the fungus can not penetrate 

 unbroken tissues and that it gains entrance to the bulbs through 

 broken roots. It seems probable that the bulbs were not diseased 

 when removed from the grouud. A short immersion in a 1 per cent 

 solution of salicylic acid or corrosive sublimate will destroy all spores 

 on the bulbs. Onion bulbs are not subject to attacks of this fungus, 

 but daffodils are, and it is said to have quite a range of dead and living 

 hosts in Japan. 



Precautionary measures, such as rotation of crops, avoidance of 

 injury to roots, destruction of refuse, etc., are recommended for the 

 prevention of the disease. When exported the bulbs should first be 

 dipped into a solution of salicylic acid. They should also be allowed 

 to thoroughly sweat before shipment. 

 18766— No. 11 5 



