PEANUT DISEASES 301 



that measurable control was achieved unless more than two sprays were 

 applied. Arthur (9) regarded attempts to control the rust with Bordeaux 

 sprays as "not achieving much success." 



DISEASES OF APPARENT IMPORTANCE IN LOCALIZED 



AREAS 



Three peanut diseases have been reported in recent years from defi- 

 nitely limited areas. It is indicated, directly or indirectly, that these 

 diseases are of importance where found. It may be assumed that such 

 diseases are a potential threat to other peanut producing regions. 



1. Sphaceloma scab (Brazil) 



A scab disease of peanuts caused by Sphaceloma arachidis Bitt. and 

 Jenk. has been reported from Brazil with pathogenicity of the organism 

 demonstrated (19). Species of Sphaceloma (Elsinoe) are associated with 

 destructive anthracnoses of many plants. 



The main symptom of this type of anthracnose is the small necrotic 

 or hyperplastic lesions on leaves, hence the name "scab" for the disease. 

 The lesions on peanuts are found predominantly on leaves, sometimes on 

 petioles and stems (19). On leaves they are found on veins as well as be- 

 tween veins. 



Sphaceloma scab was reported severe on peanuts in Brazil in 1938 

 with much less severe infection in 1939 and 1940 (39). Some varieties 

 showed apparent resistance (39). No specific control measures have been 

 recommended. 



2. Aspergillus crown rot (Queensland, Australia) 



A seedling blight or crown rot of peanuts has been described from 

 Australia and an Aspergillus sp. is regarded as the pathogen (99, 100). 

 The disease develops on plants from germination to maturity but is most 

 important as it affects the initial stand since pre-emergence losses are 

 greatest. Infection apparently takes place through lesions in the seed coat 

 and spreads from cotyledons to the stem. 



When plants approaching maturity are attacked, there is a general 

 wilt. Sometimes a mass pf spores of an Aspergillus sp. is found in this in- 

 fected tissue. No inoculation tests appear to have been made, but it is 

 assumed that this Aspergillus sp. is pathogenic. 



Observations indicate that the disease is worse under conditions of 

 high soil moisture, low fertility, unfavorable soil texture, and continuous 

 cropping to peanuts. Recommendations for control are: Avoidance of 

 excessive seed injury, seed treatment, planting of peanuts in rotation with 

 corn, small grains, or grasses (99, 100). 



