EXPERIMENT STATION REPORTS. 285 



EXPERIMENTAL WORK. 



"Two Iiimdred isolations have been made of Ps. radicicola from al- 

 falfa, clover, peas, beans, soy beans and vetch. These are to be used in 

 making extensive inoculations to study variations of the various strains 

 of the organisms. Before progress could be made with this study it was 

 necessary to devise or secure a satisfactory method of determining the 

 infecting power of the organisms. Nitrogen-free agar has been tried but 

 unsatisfactory results have been common.] Sterile sawdust has been 

 used to cover the surface of the agar. This gives indications of prevent- 

 ing contamination and providing a desirable medium in which the seeds 

 may germinate. This also retards evaporation from the agar. Another 

 method was tried with promising results. Several pieces of gravel were 

 placed in test tubes of about one inch diameter. These tubes were 

 mounted on foot. Small capillary tubes were placed in each test tube 

 for use in watering the plants from the bottom. Soils and sand were 

 tried in these. It was found that a compost rich in organic matter gave 

 better results than sand. Muck obtained from a cultivated field when 

 used to grow legumes resulted in the formation of nodules on red clover, 

 alfalfa, common beans, Canada peas, soy beans and winter vetch with- 

 out artificial inoculation. 



SUMMARY OF QUESTIONNAIRE. 



"The information obtained by a questionnaire sent to each of the ex- 

 periment stations in the United States is summarized in Table I. The 

 points about which information of particular interest was secured are 

 in order of the columns of the table as follows: (1) Whether the prac- 

 tice of inoculation is extensively practiced, (2) and (3) the legumes re- 

 quiring and not needing inoculation, (4) whether inoculation is prin- 

 cipally by soil or pure cultures, (5), (6) and (7) refer to the furnishing 

 of cultures, (8) gives an estimate of the percentage of successful inocula- 

 tions, (9) gives the answer as yes or no regarding the desirability of en- 

 couraging the practice of inoculation by pure culture, (10) gives opin- 

 ions on the reliability of commercial cultures, (11) contains answers to 

 the question, 'After once inoculating a field do you think subsequent in- 

 oculations necessary for the same legume grown in rotation with three 

 years non-legumes or legumes requiring a different strain of Ps. radi- 

 cicola?' (12) refers to extension work with inoculation and (13) gives 

 the number of bulletins or circulars published by the station on the 

 subject. , J 



