236 DISEASES OF TROPICAL PLANTS CH. 



are favourable for its development. In the seed beds 

 it should be controlled in the same manner as has been 

 recommended for tobacco, etc. (page 149). 



Early Leaf Blight. This disease is due to Cercospora 

 apii, Fr., and is widely distributed throughout the 

 celery-growing districts in the world. It first causes 

 a spotting of the leaves, which later become yellow and 

 dry. The conidia are produced in abundance and the 

 disease spreads rapidly. It can be controlled by the 

 use of Bordeaux. 



Late Blight. This disease is well known in Europe 

 and in the United States, but the writer has not found 

 a record of its occurrence in the tropics. In the 

 countries where known it is most abundant in the fall, 

 and since it occurs in the cooler part of the season it 

 may not occur in the tropics. However, the possibility 

 of its occurrence in the tropics leads the author to give 

 it mention at this time. It is caused by Septoria 

 petroselini, Desm., var. apii, Br. Cav., and appears as 

 irregular rusty brown spots which spread over the 

 entire surface of the leaf. It can be controlled by the 

 use of Bordeaux mixture. 



OKRA 



Fusarium Wilt. The okra suffers from a wilt disease, 

 which is said to be due to the Necosmospora vaswfecta, 

 (Atk.) E. F. Smith, which attacks the cotton (see page 

 108). It should be held in check to some extent by 

 destroying diseased plants, by selecting immune varieties, 

 and by proper rotation of crops. 



Leaf Spot. A leaf-spot disease due to Cercospora 

 hibisci, Tracey & Earle, has been reported from the 

 southern part of the United States, and from Cuba. 

 It causes the leaves to turn yellow and fall, weakens 

 the plant and reduces the quantity of the pods. It 

 can be controlled by the use of Bordeaux mixture 

 wherever that treatment is practical. 



