- 51 - 



Root Diseases and Soil Organisms 



S-26 The Relationship of Soil Microorganisms to the Incidence of 



Diseases in Plants , (1) To determine the interrelationships of 

 pathogenic and non-pathogenic soil microflora and the effect of 

 these relationships on the incidence and severity of plant diseases; 

 (2) to develop *more effective means of utilizing antagonistic 

 reactions and associated biological phenomena among soil micro- 

 organisms to control diseases of plants. 



Cooperating stations and agencies: Federal-grant projects - 

 Ala., S. C, Tenn., ARS 



W-38 Nature of the Influence of Crop Residues on Fungus-Induced Root 



Diseases , (l) To evaluate the chemical, physical and biological 

 effects of certain crop residues on the development or suppression 

 of root diseases; (2) to devise efficient methods and techniques 

 for the study of this type of disease; (3) to establish a 

 scientific basis for developmemt of practical control measures. 

 Cooperating stations and agencies: Federal-grant projects - 

 Ariz., Calif., Colo., Idaho, Mont., N. Mex., Oreg., Wyo. 



Tree Wilt Diseases 



NC-22 Investigations on Oak Wilt , (l) To gain, on a region- 



wide basis, essential information concerning the fungus, 

 Endoconidiophora fagacearum Bretz, causing the oak wilt disease; 

 host range factors responsible for both local and long distance 

 spread; to determine the vector or vectors; (2) to determine 

 the importance of the fungus mat; its role in the spread of the 

 fungus; and the conditions that affect its production; (3) to 

 obtain information on the longevity of the fungus under as many 

 conditions as possible and from this determine cultural practices 

 that might influence control procedures; on the effect of the wilt 

 fungus on wood from trees killed by the disease; and on a possible 

 antibiotic relationship of associated wood fungi on the oak wilt 

 organism; (A) to formulate control procedures from information 

 obtained from the above objectives. The development of chemical 

 control procedures by spraying, chemotherspeutic treatment, and 

 systemic treatment, woodlot practices by sanitation; (5) to 

 ascertain the possibility of resistance within both the white 

 oak and black oak group; (6) to develop, if possible, silvicultural 

 practices that will allow continuous woodlot production even 

 though the disease is present. Studies on harvesting methods, 

 woodlot care, and the general control measures that could be 

 made? to fit such practices. 



Cooperating stations and agencies: Federal-grant projects - 

 111., Ind., Iowa, Minn., Mo., Ohio, Wis. 



