INSTITUTE, TUSA, FOR 1916-17 107 



where a very large crop of Java indigo was obtained by its 

 use; this crop was not only heavier than those obtained on 

 control plots manured with cake, but on analysis by the 

 Indigo Research Chemist was found to contain a higher 

 percentage of indican. 



Leguminous root nodule organisms. Experimental 

 work upon cross inoculation with different strains of Ps. 

 radicicola was carried out by Mr. Joshi, First Assistant in 

 this Section. It was found that in several instances very 

 substantial increase in growth both of roots and of the 

 whole plant resulted from inoculation, although charac- 

 terized by complete absence of nodule formation. This 

 was especially the case when cultures from one species of 

 plant were used to inoculate a different species; it is sug- 

 gested that this forms a case of incompletely developed 

 symbiotic relationship due either to greater resistance to 

 invasion on the part of the host plant, to less parasitic 

 ability on the part of the invading organism, or merely to 

 a lower degree either of stimulation by the parasite or of 

 reaction to stimulus by the plant. The results of this 

 enquiry will be published shortly. 



Plant diseases. Bacterial diseases of wheat, poppy, 

 and citrus trees were under investigation during the year. 

 A Memoir on the first of these is now in the press. 



Poppy. Blackening and slimy decay of the stem and 

 leaves of the opium poppy and other varieties was found to 

 be due to bacterial rot; a description of the disease and of 

 the causative organism is in hand for publication. 



Citrus canker. This disease has been known in India 

 for several years ; some forms of it were found to be due to 

 the action of Ps. Citri well known as the cause of this dis- 

 ease in Africa and America where it has caused very wide- 

 spread and serious damage. Further investigation will be 

 made during the next year. 



IV. Indigo. 



Work on this subject has been continued in collabora- 

 tion with the Indigo Research Chemist and has afforded 



