PEANUT DISEASES 277 



material will do for first dusting, 15 to 20 pounds per acre for later dust- 

 ings. A visible coating of dust should cover the stems and both surfaces of 

 leaflets. 



6. Use any tractor or power row-crop duster which will permit di- 

 recting some dust at ground to insure bounce to cover lower surface of 

 leaflets. A short canvas hood should extend to lower edge of nozzles in 

 front and drag the top of the plants behind. This hood permits dusting 

 any time except when wind velocities are very high, and insures better 

 coverage of the plants. 



SCLEROTIUM BLIGHT OR SOUTHERN ROOT ROT 



Sclerotium rolfsii Sacc. causes three distinct diseases of peanuts : (A) 

 Root and crown rot of plants in intermediate and advanced stages of 

 growth; (B) soil-rot of pegs (gynophores) and pods of fruits approach- 

 ing maturity; (C) blue-black discoloration ("blue-damage") of the seeds 

 of Spanish- type peanuts. 



The present discussion is concerned only with the root and crown rot. 

 This is the most spectacular disease of the Spanish peanut belt of the 

 southeastern United States and, consequently, is known by a variety of 

 names. The more commonly encountered names are "southern root rot," 

 "southern blight," "blight," "white mold," (sometimes "blue mold") 

 and, in other regions, "crown rot," "foot rot" or "Sclerotium wilt." All of 

 these names indicate some recognition that the causal organism is a gen- 

 eral pathogen and not specific to peanuts. The inclusion of "southern" in 

 the name of the disease indicates that the disease is usually confined to 

 warmer regions. Of the names given the disease "Sclerotium blight" 

 seems preferable since the disease is not confined to peanuts, and is not 

 locaUzed in the "South". 



Importance. In the earlier days of peanut production in the United 

 States attacks of Sclerotium rolfsii upon the crown region received con- 

 siderable attention (2, 88, 150), but for a later period of about 15 to 20 

 years this disease attracted attention only in the Spanish peanut region of 

 Georgia (91, 92). 



Sclerotium rolfsii has been reported as responsible for deaths of plants 

 approaching 50 percent of the stand in some instances in North Carolina 

 (113) while another report listed Sclerotium blight as the cause of death 

 of as many as 10 percent of the plants (13). Reports from Texas indicate 

 considerable loss from the disease every year (1, 149). Other reports 

 listed losses from 5*. rolfsii as slight in Mississippi (108) and Virginia 

 (150). Some plant pathologists recognize the importance of the disease 



