204 



A NOTE ON CELERY LEAF-SPOT DISEASE. 



By F. J. CHITTENDEN, F.L.S. 



The disease of celery known as leaf-spot, rust, or blight, due to the 

 attack of the fungus Septoria petroselini var. apii B. and C, has spread 

 with alarming rapidity over this country since it was first definitely 

 recognised here in 1906^. 



An account of the disease and its spread, with notes on the fungus 

 that causes it and its distribution in Europe and America, are given in 

 the Journal of the Royal Horticultural Society^ and it is there shown 

 that much of the commercial " seed " offered for sale is infected with 

 the fungus. The small black fruits of the fungus appear on the walls 

 of the celery " seeds " and the pieces of stem to which they are attached 

 with considerable frequency and may be readily seen by the aid of a 

 lens. Experimental cultivation from fresh seed proved the contained 

 spores to be viable and Klebahn showed^ that spraying healthy plants 

 with the washings from affected seeds led to the infection of the plants 

 with the disease. 



The author was led to suspect the seed as the principal, if not the 

 only source of infection, by the curious distribution of the earlier 

 attacks, the incidence of the disease on certain strains of celery, the 

 absence of any records of attack upon wild plants, and the fact that so 

 far as enquiry showed, the seeds from which the diseased plants had been 

 raised had been purchased from one or two sources. Against it was the 

 fact that all the earlier attacks had been noticed late in the year, gener- 

 ally from September onwards, though one or two attacks had been 

 seen in July. At this season the disease had obtained such a hold upon 

 the plants that spraying methods proved almost entirely inadequate 

 to prevent its spread and total loss of crop frequently resulted. Later, 

 attacks of a slighter nature were noticed nearer the beginning of the 

 growing season and spraying with Bordeaux mixture at frequent intervals 



1 Chittenden, F. J. Journal R.H.S., xxxii (1907), p. cxii. 



^ Chittenden, F. J. Celery Leaf-Spot, Journal R.H.S., xxxvii (1911), p. 115. 



^ Klebahn, H. Krankheiton dea Selleries, Zcits. f. Pflanzcnkr. (1910), p. 4. 



