720 Journal op the Department op Agriculture. 



are altogether destroyed. Alfected leaves show a tendency to curl 

 inwards, and are more or less twisted and distorted. 



Spots on calyces, pedicels, and young parts of the stem are similar 

 in character to the leaf spots. On the calyx they may be numerous, 

 hut verj' minute and scattered, or less numerous and up to the 2-3 mm. 

 diameter; or they may form elongated streaks up to 5 or 6 mm. long. 



Cankers are produced on older parts of tlie stem, es])ecially Avhere 

 the tissues have been somewhat injured by friction or otherwise. At 

 first there appear irregular, dark gieen, water-soaked areas, Avhich later 

 become corky-looking, slightly raised, roughened, and with numerous 

 small longitudinal cracks. 



The surface has the appearance of having become blistered or 

 raised by abnormal tissue development underneath, with subsequent 

 cracking of the blistered areas. Cankers of irregular form and* 

 1-2 cm. in diameter are not uncommon. The discoloration does not 

 penetrate with the wood; it is aijpareutly confined to the cortex and 

 quite superficial. 



In the field infected fruits are usually found immediately below- 

 diseased leaves, and are doubtless infected during rainy weather by 

 rain-drops which fall on infected leaves and subsequently drip on to 

 the young fruit. The majority of the iruit spots are at the stalk end, 

 but they are also found scattered over the sides and less frequently 

 on the blossom end. 



A very minute green or brownish blister is the first indication 

 of infection; this blister may remain minute, about 1 mm. diameter, 

 or may increase in size up to about o mm., and become considerably 

 raised above the normal fruit tissue. Occasionally, presumably w^hen 

 weather conditions are unfavourable, infection does not proceed 

 further, and when the fruit is ripe these minute blister-like spots 

 have almost the appearance of fly-specks. 



In the large majority of cases the point of infection becomes 

 surrounded by a dark green water-soaked area which spreads consider- 

 ably, and then begins to discolour from the centre. The centre 

 becomes dark brown, a water-soaked margin about 1 mm. wide is still 

 apparent, whilst the organism is active. Finally the epidermis 

 ruptures in the centre, showing whitish-brown over the discoloured 

 tissues like the broken edges of a blister. The spots are hard and 

 scabby in texture, and usually slightly convex, although in mature 

 fruit they may lie in slight depressions owing to arrested growth at 

 the point of infection. 



vSingle scabs are usually not more than 5 mm. diameter, but they 

 are often so numerous and close together that they coalesce, forming 

 large, scabby areas several centimetres in extent. As the fruit 

 ripens the tissues round the infected areas remains green, forming a 

 green rim round the scabs, which is conspicuous on the red fruit. The 

 rifts in the epidermis become extended in cases of severe infection 

 and whitish-brown cracks are formed, many of them over 1 cm. in 

 length, and extending into unaffected tissues. These open the way 

 for putrifactive organisms, and the fruit usually rots in a few days 

 after ripening. 



Thus the disease not only disfigures the fruit and reduces its 

 market value, but seriously affects its keeping qualities. 



