38o 



Journal of Agriculture , Victoria. [lo June, 191 i. 



aftected the fruits at this stage. The fruits were the first portions of the 

 plant to be attacked by the wind-borne spores. Tomatoes were found 

 affected at all stages of growth, from the tiny fruit not the size of a pea, 

 to the full-grown and large-sized lobed fruit. The symptoms are generally 

 well-marked. There is a brownish discolouration, at first in patches, with 

 a tendency to become mottled ; and, when the fruit is sliced, this is seen 

 to be due to the discolouration of the pulp extending more or less 

 throughout. 



A very simple way in which artificial infection may be brought about, is 

 tc place sporangia in a small phial of water. After being well shaken, 

 a drop is placed on the skin of the potato or tomato, and a cut or stab 

 made through the drop into the skin. Twenty healthy potatoes were 

 infected at the same time in this way, and all became diseased, every one 

 showing signs of it in about seven days. When the skin is unbroken 

 there is not the same certainty of infection. 



After the discovery of blighted tomatoes in Victoria, plenty of fresh 

 spores Avere available, and an experiment was carried out to test the mutual 

 infection of spores from potato and tomato under exactly similar con- 

 ditions, when applied to the unbroken and broken skin. In each case 

 there was only a single point of infection, and each specimen was placed 

 by itself in a closed jar lined with moist blotting-paper, on joth April, 

 igii. 



No. 



One of the healthy tomatoes and potatoes was kept separately under 

 moist conditions, without any development of disease. In nine days, two 

 c^ the tomatoes and two of the potatoes with broken skin, as well as one 

 of the potatoes with unbroken skin, produced the fructification of the Irish 

 Blight fungus. At the end of fourteen days, a tomato with unbroken 

 skm also produced the fructification, but no further developments were 

 observed at the end of a month, and the experiment was considered closed. 

 Thus, a tomato and a potato with unbroken skin, inoculated with spores 

 from a potato, were not infected, owing to some individual peculiarity, 

 but in a previous experiment this infection was successful, and the fruc- 

 tification of the fungus appeared in both instances in sixteen days. 

 Appended is a short account of the behaviour of each specimen. 



Explanation of Plate. 

 :S. 1.— Two tomatoes from Yannathan, taken from the field, and showing luxuriant fructification on 

 unbroken skin. 

 Fig^. 2. — First specimen of Ijliffhted tomato obtained in Victoria. 



Fig. 3.— Cross section of tomato, showing browning of tissue extending from outside inwards, and 

 producing sporansjia in fiiiit cavities. 

 4. — Section lengthwise of tomato from Gelliondale, showing browning of tissue extending from 

 circumference. 



