48 



] ounial of Agriculture. 



[lo Jan., 1910. 



IRISH BLIGHT IN TOMATOES. 



D. McAlpiue, Vegetable Pathologist. 



A diseased tomato was forwarded to me by Mr. J. G. Turner, Senior 

 Inspector of Fruit Exports and Imports, from a line of 26 cases imported 

 from New South Wales and arriving here on 22nd November. The stalk 

 end was of the ordinary red colour and healthy looking, but the blossom 

 end was of a dirty-green colour mottled with brown. On cutting the 

 tomato across, it was found that the flesh beneath the discoloured skin 

 was of a brown rusty colour and extended towards the centre as shown 

 in Fig. 2. After being cut for some little time there was a rotten dis- 

 agreeable smell. On placing slices of the diseased tomato in a moist 

 chamber, the fructification of the Irish Blight developed luxuriantly on 

 the cut surface in 22 hours. The time taken for the development of the 

 fructification of the fungus on the cut surface of a diseased tomato varies 

 considerably, probably owing to the varying degrees of heat and moisture. 

 Another slice from the same diseased tomato was placed in a moist cham- 

 ber and closely observed. In this instance the fructification developed 

 on the cut surface in 7^ hours, and this is the shortest time vet recorded. 



t. TOMATO AFFECTED WITH IRISH BLIGHT. 2. SECTION OF SAME TOMATO. 



It is exactly the same fungus in the tomato as that causing potato 

 blight, and this was proved conclusively by infecting a healthy potato 

 with the spores of the fungus from a diseased tomato and a healthy tomato 

 was infected with the spores of Irish Blight obtained from one of the 

 diseased potatoes grown in Beech Forest. This fungus may attack other 

 members of the potato family as well as the tomato, but the latter is the 

 only one of economic importance which requires to be specially attended 

 to. It is not always sufficiently realized by growers how closely related 

 potatoes and tomatoes are, for the one can be used as a stock for the 

 other. Potato plants will grow on tomato plants, and tomato plants on 

 potato plants. If the potato is used as the root, both tomatoes and 

 potatoes may be produced, but if the tomato is the root, neither potatoes 

 nor tomatoes will be developed. 



It is not only the potato industry which is threatened by the Irish 

 Blight, but also that of the tomato, and when it is remembered that the 

 value of the tomato crop is reckoned to be worth over ;^i8,ooo in 1908-9 

 to Victoria, it can readily be understood that the disease is not one to be 

 trifled with, and that it should be stamped out wherever possible. That 

 the risk to which the tomato-grower is exposed is not exaggerated, mav 

 be seen from the losses sometimes incurred from this cause alone. It is 



