216 



Diseases of Economic Plants 



colored areas in the bark, often extending part of the way 

 around the stem. Later the roots may rot from secondary 

 causes. 



Upon the diseased spots are fine mycelial strands, espe- 

 cially abundant under humid conditions. Soon these strands 



unite into tufts, which 

 round off, become hard 

 and smooth, and 

 change from white to 

 yellow, and finally to 

 dark brown. These 

 bodies, the sclerotia, 

 are about as large as 

 mustard seeds. At- 

 tacks usually begin 

 when the pods are 

 forming and continue 

 throughout the season. 

 This disease has been 

 found in many South- 

 ern states upon a wide 

 range of plants. See 

 p. 23. 



The application of a 

 clear, preventive fun- 

 gicide, such as ammo- 

 niacal copper carbon- 

 ate, to the ground at 

 the base of the plant, and where any part touches the 

 ground, so that it can soak into the ground near by and 

 cover the stem itself, has proved beneficial. The first ap- 

 plication should be made at the earliest sign of blight, or 

 still better, in anticipation of it, and should be followed by 

 other apphcations at intervals of two to three weeks. Bor- 

 deaux mixture is not suitable, since the effective material is 

 filtered out by the soil. 



Black-mold (Macrosporiuni sp.). — This malady renders 



Fig. 118. — Pepper plant showing fun- 

 gus of Southern-blight. After Fulton. 



