INSTITUTE AND COLLEGE, PUSA, FOR 1912-13. 61 



parasite was found to infect the corms and to cause consi- 

 derable injury after the crop is lifted. Pure cultures were 

 grown in 1912, and a large series of inoculation experiments 

 carried out, but the species is much more restricted in its 

 choice of hosts than the castor parasite. 



A serious outbreak of potato blight (caused by Phytoph- 

 thora infestans de Bary) occurred in the Gangetic Plain, 

 where the disease has not been reported since 1902. The 

 outbreak is probably to be attributed to the fact that the 

 local seed supply failed, in a great measure as a result of 

 damage caused by the potato moth. A large import of 

 hill seed occurred at the beginning of the cold weather and 

 no doubt introduced the fungus, which is endemic in the 

 hills. Mr. Dastur has obtained pure cultures of the para- 

 site and is testing its temperature relations, as this appears 

 to be likely to prove the most important factor in its con- 

 trol. 



Rhizoctonia. 



The results of Mr. Shaw's work on this genus of soil- 

 dwelling parasites, referred to more fully in last year's 

 report, were published during the year. He has continued 

 his investigations, particularly with forms parasitic on 

 lucerne and Delphinium. It is evident that great confu- 

 sion of species exists in the published literature of the 

 genus and his researches should do much to clear this up. 

 It is of interest to record that a severe attack of opium 

 poppy blight, which has generally been supposed to be 

 caused by Peronospora arborescens, was found to be due 

 last season to Rhizoctonia. It is hoped that Mr. Shaw 

 will be able to continue his work on this, after his return 

 from Madras. 



Wheat rust. 



Wheat rust was prevalent in Bihar last season and some 

 interesting observations were made in selected areas at 

 Pusa, on the influence of soil moisture and density of 

 growth on the disease Orange rust (Puccinia triticina) 



