W. F. Bewley 159 



three different organisms which appear to be Phytophthora terrestria 

 (SherbakoiT) 1 , Ph. cryptogea (Pethybridge) 2 and Rhizoctonia solani (Kuhn) 

 Duggar 3 respectively, though precise identification is not possible until 

 comparisons of pure cultures are completed. Ph. terrestria also produces 

 "buck-eye" rot of tomato fruits, stem rot and "foot rot" of the tomato, 

 and stem rot of the lupin. Ph. cryptogea has been described 4 as producing 

 "foot rot" of the tomato and aster, and not infrequently it is very 

 destructive to antirrhinums and lupins. Rhizoctonia solani is regarded 

 as a universal soil organism, which attacks young plants. 



The Water Supply 



Observations in nurseries where epidemics of "damping off" and 

 "foot rot" have been in progress led us to suspect the water as being 

 an important source of infection. Preliminary experiments on seedlings 

 on which water suspected of contamination had been used confirmed 

 this suspicion. We have therefore undertaken an extensive analysis of 

 nursery waters in the Lea Valley to ascertain what organisms pathogenic 

 to the tomato they contain. The results, which will be given in a further 

 communication, show that while some waters are practically free from 

 pathogenic organisms, others contain the spores of many tomato 

 parasites. The problem of pure water supply is exceedingly important 

 and requires very careful investigation. One important and obvious 

 precaution is to avoid all danger of polluting the well by surface drainage 

 from the nursery, or any allotment, garden, etc. 



Experimental. 



An examination was made of diseased seedlings from various 

 nurseries in the district. The pathogenic organisms were identified, 

 isolated in pure culture and tested for pathogenicity. 



The dominating pathogen, here called Phytophthora "A," appeared 

 to be identical with Phytophthora terrestria described by Sherbakoff 5 in 

 America as producing "buck-eye" rot of tomato fruits and stem rot of 

 citrus trees and lupins, and is probably identical with Ph. parasitica 



1 Sherbakoff, C. D. Phytopath. vol. vu, No. 2, 1917. 



2 Pethybridge, G. H. and Lafferty, H. A. Sci. Proc. Roy. Dubl. Soc, vol. xv (N.S.), 

 No. 35, 1919. 



3 Duggar, B. Ann. Mo. Bot. Gard., vol. n, 1915. 



4 Pethybridge, G. H. and Lafferty. H. A., loc. cit. Spinks, G. T. Ann. Rept. Agr. and 

 Hort. Res. Sta., Long Ashton, Bristol, 1917. Robinson, W. Ann. App. Biol. vol. n, 1915. 



6 Sherbakoff, C. D Loc. cit. 



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