240 DISEASES OF ECONOMIC PLANTS 



should be removed, and burned if not marketable. Treat 

 also as for wilt. 



Soft rot. — This rot occurs widely and causes large loss, 

 placing it among the worst ginseng diseases. The root 

 decays rapidly, is sticky and ill smeUing. The leaves color 

 red and yellow and soon die. 



Damping off {Rhizodonia, etc.). — Damping off is largely 

 avoided by thorough ventilation, and the avoidance of ex- 

 cess of moisture in soil and air. Stirring the soil to hasten 

 drying aids. See p. 61. 



Leaf anthracnose,pestalozziose(Pestaio22ia/?merea,Desm.). 

 — A disease more destructive to young plants than to older 

 ones is pestalozziose,^ which appears as a black, velvety 

 growth at the bases of the leaves and flower stalks, causing 

 them to die and fall off. 



Spray as for alternariose. 



End rot, fiberrot (Thielavia hasicola (B. & Br.) Zopf.). — 

 This is especially bad upon seedlings, resulting in sudden 

 wilting, which causes them to bend over and dry up. The 

 fine roots are affected as are the roots of tobacco. 



GOLDENSEAL (Hydrastis) 



Blight {Alternaria sp.). — Spots occur upon the leaves 

 The disease seems to be identical with that of ginseng. 



HOP 



Powdery mildew (Sphcerotheca Humuli (DC.) Burr.). — 



This powdery mildew, while serious in many parts of Europe, 



has been seen but rarely on the hop in America, and has 



never been reported as seriously injurious. It is recognized 



1 Reed, H. S., Mo. Agr. Exp. Sta. Bui. 69, October, 1905. 



