498 Journal of Agriculture, Victoria. [ 11 Aug., 1919. 



II.-TOMATO DISEASES. 



Leaf Spot of Tomato (Septoria lycopersici Speg.) 

 C. C. BrlUlehanl-. Vegetable Faihologisf. 



The fuugus causing the " leaf spot" disease of the tomato was first 

 described by Spegazzini, in Fung. Argt., Pug, IV., No. 289, 1882. 

 It would seem from records relating to the disease that it was present 

 in many places, but had not been brought under the notice of plant 

 pathologists. 



Specimens in our herbarium (Exsicc. No. 93), Briosi and Cavara, 

 1889, still sho-vv the leaf spots, pycuidia, and spores. 



Brief mention of the disease is made by Professor A. D. Selby, 

 Ohio, Bulletin No. 73, 1896, under the heading " Tomato Leaf Blight: 

 A New Arrival in the State of Ohio." Prior to Selby's paper, the loss 

 caused by the disease in some of the States was considerable. 



In Australia the disease, was first recorded by Dr. N. A. Cobb 

 {Agiicultiiral Gazette, New South Wales, Vol. XIII., page 410, 1902.) 

 Dr. Cobb mentions that the disease was present during the summer of 

 1901, and also to the apparent rapidity of dissemination. The second 

 Australian record was by Mr. McAlpiue, in the Journal of the Depari- 

 vient of Agriculture of Victoria, Vol. II., page 70, 1903. Mr, 

 McAlpine says: — " Though this particular disease has not ccme under 

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

 for some time past." Our records show that the disease has affected 

 tomatoes in all parts of Victoria, and this would bear out Mr. 

 McAlpine's statement that the leaf spot disease was probably in 

 Victoria for some time prior to' 1903. 



Symptoms of the Disease. 



On Leaves. — The first indication of attack to be noticed is an un- 

 thrifty appearance of the plant. If the lower leaves be carefully 

 examined numerous minute water-soaked spots may be observed. These 

 spots are at first inconspicuous, and no definite disecloration is apparent 

 in this early stage of attack. Later the spots enlarge and assume a 

 more or less circular outline, and become darker than the normal leaf 

 tissue. As the disease progresses the affected leaves assume a dark- 

 brown, or greyish-brown colour, harden, and in hot dry weather become 

 brittle. 



In some cases the number of leaf spots may be few and small, and 

 in others the points of infection may be so numerous and close together 

 that the whole leaf is involved, turns brown, shrivels, and in time 

 breaks up. 



When the infection is light, there may l^e from three to six spots on 

 the leaf. If these spots be closely examined minute black dots are seen 

 in, or towards the centres of the affected area. These are the spore 

 cases, or pycnidia, whicli contain the s])ores, and vary in number from 

 three to ten or more. 



When the whole leaf is involved, withering and death take place 

 rapidly, and the spore cases are not formed till autumn or early in the 

 following spring, when thev develoD in preat numbers, especially if 

 the vines be piled in heaps and the leaves kept moist. 



