48 W9t AND MILDEW IN INDIA. 



Uredine (the order to which rust belongs).* I have endeavoured to 

 get definite information on this important subject, but without 

 success ; and my own continuous and specially directed observations 

 in Simla have failed to bring to light the existence of any Uredine 

 on the summer crops which alternate with our winter cereal crops. 

 I have, for example, visited fields in the summer months with the 

 special purpose of finding some species of Uredine, since I knew 

 (also by personal inspection) that the wheat crops immediately pre- 

 ceding have been enormously rusted and mildewed, and found no 

 trace of any ; and then I have again visited these same fields when 

 they were again bearing wheat crops succeeding the above-men- 

 tioned summer crops, and have found them again largely rusted. I 



have also looked on wild grasses for surviving rust, but have found 



none. 



An investigation into the causation of rust would be by no 

 means a simple one. It will be gathered from what I have already 

 written that the subject is surrounded by many difficulties. Still 

 there is, I think, every hope that a patiently conducted study of it 

 would be rewarded with success, and, the cause being known, we 

 would be in a position to apply remedies. Before light is shed 

 upon its true cause, probably much destructive work must precede 

 constructive. In illustration of my meaning, I may draw attention 

 to Sleeman's view that the rusting of wheat was due possibly to the 

 transference of the disease from " Ulsee ,f (linseed). At the time 

 he wrote, such an explanation was plausible enough, and even now 

 (with the data he had) it is within the bounds of possibility. 

 Nothing is known, so far as I am aware, even at the present time, 

 of the nature of that disease on " Ulsee " ; but, being struck with 

 his explanation, I obtained a specimen of such diseased "Ulsee" 

 from Dumraon (whence I also at the same time got the mildewed 

 wheat specimens above referred to), and found it to be a species of 

 Melam psora \ (a genus certainly of Uredine®), and this renders it 

 almost certain that the disease on " Ulsee " is in no way related to 

 the rust of wheat. This is an instance of partial destructive work 

 clearing the way towards a final solution of the rust question 

 partial, because it still remains to be proved that the teleutospores 

 borne on the " Ulsee" do not in fact attack the wheat plant. It is 

 extremely improbable that they do. Then, again, we must clear 

 our ideas regarding the part played by the barberry. That it does 

 not play any considerable part here in India appears highly pro- 

 bable ; but that it does play some part is certain, from the occur- 

 rence of JP. fjraminis in Jeypore. 



In conclusion, I must express my thanks to many friends for 

 their assistance in procuring specimens for me of rusted crops, and 

 for much valuable information on the prevailing local ideas regard- 

 ing the causation of this blight. These are often quaint, but as 



* Since this was written, I have obtained Puccinia sorghi Pers., on 

 Sorghum vidgare; but although Sorghum is usually a summer crop, yet the 

 specimens I obtained from the Poona district were on a winter crop. 



t Probably Melampsora lini Pers. 



