158 Diseases of Greenhouse Crops 



Control. The disease may be kept in check by 

 spraying with a weak solution of Bordeaux mix- 

 ture. 



Southern Blight 



Caused by Sclerotium rolfsii Sacc. 



Southern blight, a disease that attacks a large va- 

 riety of hosts, is a serious melon disease in the South- 

 em States. The injury in most cases is confined to 

 the foot of the stem, the girdling and rotting of 

 which finally causes the death of the affected plant. 

 In the case of the cantaloupe, the fruit itself is at- 

 tacked, infection usually taking place at a point 

 where it touches the ground. The disease appears 

 first as a slight soft spot which enlarges quickly, 

 changing the entire mass of the fruit to a mushy 

 pulp. The exterior of the affected melon is rapidly 

 covered with a white cottony growth consisting of 

 the mycelium of the fungus. Later there appear 

 numerous whitish bodies known as sclerotia which 

 turn yellowish and then brown. They help to carry 

 the fungus over the winter. For methods of con- 

 trol, see pp. 32-43. 



Root Knot, see Nematode, p. 28 (fig. 31). 



