10 Aprd., 11H9. 1 Tomato Diseases. ■ 231 



TOMATO DISEASES. 



Bi/ C. C. Brittlehank, Plant Pathologist. 

 1. 

 The tomato industry in Victoria has, within the past ten to fifteen 

 years, greatly increased, and it would be interesting to know the area 

 under and returns from this crop, but no records have been kept. 



As might be expected, when such a crop has been grown continuously 

 in certain areas, and under forced conditions, diseases have become estab- 

 lished, which claim a greater or less percentage of the yield. Thirty 

 years ago (1886) paddocks of 30 or 40 acres of tomato plants were 

 practically free from disease. Since then, however, several diseases 

 have developed, and the object of this article is to describe briefly their 

 appearance and the methods of control, so far as they are known at the 

 present time. 



The following diseases of tomato plants are found in Victoria : — 

 Alternaria solani, E. et M. — " Leaf mould," or " Target spot." 

 Septoria lycopersici, Speg. — " Leaf spot," " Eust," " Leaf blight." 

 Fusarium solani (Mart), Sacc. — "Wilt," "Sleepy disease." 

 Sclerotinia — " Sclerotium disease." 

 Rhizoctonia solani, Keuhn — ■" Root rot." 

 Phytophthora infestaus, De Bry — " Irish potato blight." 

 Bacillus solanacearum, E. F. Smith — " Brown rot," " Wilt." 



A New Tomato Disease — " Spotted Wilt." 



To the list above must be added a disease which has, within the last 

 three years, appeared in tomato plants. The origin of this disease, as 

 well as how and whence it was introduced, is, .so far, unknown. Unfor- 

 tunately, up to the present time no causal organism has been isolated, 

 and consequently no method of control has been devised. However, it is 

 the intention of the Science Branch of the Department of Agriculture 

 t(j carry out experiments during the coming year, with the object of 

 endeavouring to ascertain the cause of the disease and the method of 

 controlling it. 



A feature of this new tomato disease is that its most virulent period 

 is during the prevalence of swarms of " Canaiy flies," or " Jassids." 

 During the season just ended it was noted that as the Jassids decreased 

 in numbers the disease waned, and the later plants were only slightly 

 aliected, while in many cases they have recovered to a great extent, but 

 odd plants are still developing the disease. jSTumbers of early plants, 

 which became diseased about January, have recovered also. As this 

 disease is the most serious that the tomato grower has to contend against, 

 and has been the cause of heavy losses in recent seasons, I shall deal with 

 it first. It is well to have a common name for every tomato disease, and 

 I propose that of " Spotted Wilt " for this latest one, from the spotting 

 and subsequent wilting of the attacked plants. 



Spotted Wilt was first observed during the 1915-16 season, when the 

 injury was slight owing to the restricted area over which the disease had 

 spread and to the comparatively small number of plants affected. In 

 the folloAving year the number of diseased plants had increased to an 

 alarming extent. The present season (1918-19) has, to say the least, 

 been disastrous, and fully 50 per cent, of suburban garden plants have 



