VII 



TOMATOES 213 



Leak. This is another storage disease, and is due to 

 Rliizopus nigricans, Ehrbg. It sometimes causes con- 

 siderable loss. The organism cannot enter the plant 

 except through wounds. It lives in the soil and attacks 

 white potatoes, sweet potatoes, apples, and other plants. 



The dodder or love vine (Cuscuta epithymum) has 

 been reported as growing on the potato in Victoria, 

 Australia. It does not do a great amount of damage. 



Nematodes. These pests, which are so widely dis- 

 tributed over the world and attack so many species 

 and varieties of plants, are also found on the potatoes. 

 They cause the formation of small pimples, each sur- 

 rounded by a slight depression. The tip of this pimple 

 is frequently broken, and the tissues below are dis- 

 coloured for a short distance. While the injury itself 

 may be slight, it gives a most favourable condition for 

 infection with other organisms. Diseased potatoes 

 should not be used, and such rotation of crops should be 

 practised as will renovate the soil of these pests. 



TOMATOES 



Tomatoes in the tropics are subject to many diseases, 

 which are caused by the same organisms as the diseases 

 in the temperate zones. 



Black Rot, Blossom End Rot, Point Rot, This is a 

 fruit disease which originates as a small dark green, 

 watery, irregular spot, usually at the tip or blossom end. 

 The spot enlarges, and since the growth is stopped at 

 that point, the spot soon appears to be sunken. After 

 a few days the spot may appear dry and somewhat 

 shrivelled. The disease is very destructive, frequently 

 destroying a large percentage of the crop. It is well 

 known throughout the United States and in Cuba. 



The cause of this disease is disputed. It has been 

 attributed to Alter naria fasciculata, (C. & E.) J. & G., 1 

 but the more recent studies of Smith of Massachusetts, 

 on what is probably the same disease, indicates that the 



1 Synonyms, Macrosporium tomato, Cooke ; Macrosporium solani. 



