INSTITUTE AND COLLEGE, PUSA, FOR 1912-13. 91 



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in one set lack of drainage should allow of accumulation 

 of the toxins produced, whilst in the other continuous per- 

 colation removed them in solution. The results completely 

 verified expectation, as not only was growth seriously in- 

 terfered with in the undrained pots, but the root forma- 

 tion in the drained set showed that the toxins carried 

 down by the percolating water had inhibited root growth 

 m the lower soil, whereas in the undrained series more root 

 development took place below than above. No symptoms 

 of " Ufra " appeared, but Dr. Butler has now demonstrated 

 conclusively the connection between this disease and the 

 presence of nematodes in the plants, nor does it appear 

 that soil conditions adverse to healthy growth render the 

 plants more liable to attack. 



(3) Tobacco. — The work on Tobacco Wilt in the Rang- 

 pur District was concluded and a Memoir on the subject 

 published in the Bacteriological Series. 



(4) Indigo. — Plants of Java variety were grown and 

 kept under observation for symptoms of wilt in order to 

 determine a possible bacteriological origin of this disease; 

 this work will go on through current season. 



(5) Potato Rot. — An extensive series of investigations 

 was carried out, mainly by Mr. N. V. Joshi, First Assist- 

 ant, as to the cause responsible for the very common rotting 

 of tubers in store. The Economic Botanist to the Govern- 

 ment of Bihar and Orissa, at whose instance this work 

 was undertaken, provided samples from various godowns 

 in Bihar, and others were received from Poona. Two 

 rotting bacteria were found to be present invariably, and 

 these appear to be normal in Indian soils. It was found 

 that rotting could take place in presence of these bacteria 

 either if the dry tubers suffered mechanical injury or if 

 the uninjured tuber were kept under conditions in which its 

 surface could remain moist for a few hours. Thus tubers 

 stored in sand to keep out potato moth can be attacked 

 if the rotting organisms are present, either through 

 bruising due to careless handling or by reason of the sand 

 not being perfectly dry, or by contact between a rotting 



