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FUNGOUS DISEASES OF PLANTS 



LI. SEPTORIA: OTHER SPECIES 



Septoria Lycopersici Speg., leaf blight of the tomato. The 



tomato is attacked by several leaf fungi which may become destruc- 

 tive, and of these fungi the one most injurious throughout the 

 range of tomato culture is the organism causing what is known as 

 leaf blight. The leaves are the parts most severely affected, and on 

 these parts appear numerous small angular spots pale in the centers 



FIG. 180. TOMATOES DEFOLIATED BY THE LEAF BLIGHT FUNGUS 

 (Photograph by H. H. Whetzel) 



and with colored borders. The affected leaves have a tendency to 

 curl dorsally throughout their length, eventually drying and falling. 

 Petioles and twigs may also be affected, and small, elongate, dark 

 spots may appear on the fruit. 



The pycnidia are found on the upper surfaces of the leaves in 

 the larger spots. It is probable that the fungus passes the winter 

 in the old leaves and other refuse. 



The use of Bordeaux mixture during the early part of the 

 season has generally resulted in successful prevention. 



