214 DISEASES OF TROPICAL PLANTS CH. 



real cause is Fusarium solani, Mart., and that the 

 Alternaria is secondary and saprophytic. However, 

 some workers believe that the true cause is Bacillus sp. 

 It is possible that what appears to be the same disease 

 may be due to different organisms in different localities, 

 but that the secondary fungi are the same throughout 

 very wide ranges. This disease is most severe after 

 periods of drought and may be due to climatic conditions. 

 It is very doubtful if the disease can attack the fruit 

 except through wounds. Over-fertilization, especially 

 with nitrate of soda, makes the fruit more susceptible to 



the disease. The use 

 of Bordeaux is not 

 especially successful. 

 The growers should 

 endeavour to select 

 seed from immune 

 plants. 



Anthracnose. This 

 disease (Figs. 71, 72), 

 vvhich is frequently 

 spoken of as the ripe 

 rot, is caused by Gol- 

 letotrichum phomo- 

 ides, (Sacc.) Chester. 

 It attacks the fruit 



when nearly ripe, causing discoloured, sunken spots. It 

 spreads rapidly in damp, warm weather, causing 

 decay of the fruits and resulting in heavy losses. The 

 only practical remedy is hand-picking and destruction 

 of the diseased fruits, thus preventing the formation 

 of spores and the spread of the disease. 



Brown Rot of Green Fruit. This disease has been 

 reported from Cuba. It originates as a spot on the 

 green fruit and causes a rot before ripening. It appears 

 to be due to a Wiizoctonia, and is most destructive in 

 wet weather. Careful draining, a thorough cleaning 

 and burning of the rubbish in the field, and rotation of 

 crop would no doubt prove helpful. 



FIG. 71. Tomato affected with anthracnose, 

 Colletotrichum phomoides. 



