Family Araliaceae in 



Symptoms. Black rot is apparently a root disease 

 only. Roots dug from affected areas are coal black, 

 with no rootlets, but with intact bud, which, however, 

 is also blackened like the root. On the surface of the 

 latter are found numerous sclerotia the size of a small 

 pea. On cutting open a diseased root only the outer 

 rind is found to be blackened, while the center re- 

 mains white, spongy, and watery. The affected root 

 does not soft rot, but becomes very bitter in taste. 

 If left over in the soil for two seasons the root will 

 turn black all through, shriveling and decaying. 

 Black rot works only in cold weather of early spring 

 or late fall. In structure Sclerotinia panacis greatly 

 resembles S. libertiana (fig. 19 p). 



Control. Remove the diseased plants and the sur- 

 rounding healthy ones on a strip a foot wide. Drench 

 the soil with a heavy application of one part com- 

 mercial formaldehyde in 50 parts of water about I 

 gallon per sq. ft. 



Fiber Rot (Rust) 



Caused by Thielavia basicola (B. and Br.) Zopf. 



Symptoms. The manifestations of fiber rot depend 

 largely on the age of the root and the part attacked. 

 With seedlings and in dry weather the leaves lose 

 their dark green color, become pale, tinting into 

 shades of red, and finally the leaflets wither and the 

 stems wilt. Often the leaves of infected seedlings 

 take on a purple bronze color. In wet weather the 



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