70 Agricultural Journal of Victoria. 



TOMATO LEAF SPOT. 



(Scptoria lycopersici, Speg.) 



By D. Me Alpine. 



Early in April last, some badly spotted and unhealthy tomato leaves 

 were forwarded for examination by Inspector Cronin from the Tally Ho 

 district. The general appearance of the diseased leaves is well seen 

 in Fig. 1 of the accompanying plate, reproduced from a photograph by 

 Mr. G. H. Robinson. The. plants were grown in a very exposed 

 situation, and probably were somewhat weakened before being subjected 

 to the attacks of the leaf s])ot fungus. 



Though this particular disease has not previously come under my 

 notice in Victoria, very probably it has existed here in a mild form for 

 some time past. Dr. Cobb, of New South Wales, recently mentioned 

 a leaf disease of the tomato as existing in that State, and which is 

 apparently the same as the one we are now dealing with. 



The original home of this fungus ajjpears to be Argentina, for the 

 first record of its existence was made on tomatoes there in 1882. In 

 1888 it was noted in Italy, while in 1894 such a severe outbreak 

 occurred in the United States that the tomato crop was almost entirely 

 destroyed in many districts. 



Symptoms and Nature of the Disease. 



It causes spots not only on the leaves, but also on the stems and 

 fruits. On the leaves it occurs as large irregular spots, sometimes 

 so numerous as to cover the entire surface, and of a dirty- brown oi* 

 ashy-grey apjiearance. The attacked leaves lose their green colour 

 and become languid, either dropping off or withering on the stem. 

 The spots are thickly studded with minute black dots, just visible to 

 the naked eye, and these constitute the fructification of the fungus. 

 The calyx of the fiower may also be attacked, and there is a consequent 

 failure to set fruit. 



The little black points are the spore cases, one of which is shown 

 in Fig. 2 allowing the spores to escape. The spores are produced in 

 great profusion, and are elongated, slender, rod-like, jointed bodies, 

 of a clear colour, and with granular contents (Fig. 3). On an average, 

 it would take about three hundred of them end to end to make up 

 one inch. The formation of the spore cases is much accelerated in 

 naoist and muggy weather, and when the diseased leaves fall to the 

 ground, where they may renaain continuously wetted for several days, 

 the production of spores is rapid and profuse. 



Treatment. 



Spraying, when begun early, has been found effective ; but there 

 are other precautions which may be taken so as to render this trouble- 



