On the Diseases of Wheat. 



9 



These last may be repeated, by washing: the seeds clean after they 

 have been steeped, to remove any of the mixture that may adhere 

 to the surface. 



No. 11. Prepared as No. 8. 



— 12. , J , , 9. 



— 13. , , , , 10., &c. &c. 



Section V. — On the Rust, Red-rag, Red-robin, Red-gum. 

 (Uredo rubigo, and Uredo linearis.) 



I believe that under the names here quoted, agriculturists 

 have comprehended the attacks of what systematic botanists con- 

 sider to be two distinct species of fungi ; and which the expe- 

 rienced eye of the microscopic observer was alone likely to separate. 

 They form yellow and brown oval spots and blotches upon the 

 stem, leaf, and chaff ; and when the spores have burst through the 

 epidermis they are readily dispersed. Like those of the bunt- 

 fungus, and smut- fungus, they consist ol" very minute grains, but 

 their colour is different, varying from orange-yellow to brown, and 

 their shape is not so perfectly sphaerical, especially those of U. line- 

 aris, which are usually oblong. Both these fungi are very com- 

 mon on corn and grasses. I have within the last two months (of 

 July and August) seen more of the Red-rag ((7. rubigo) as it is 

 here called, than of any other, of these corn-pests. It abounded 

 in the form of an orange powder which exuded from the inner 

 surfaces of the chaff-scales, but was scarcely if ever to be seen 

 in the skin of the. seed ; it might also be traced in patches 

 beneath the epidermis of the straw, but I did not observe that it 

 had burst through the epidermis anywhere, excepting on the 

 inside of the chaff. It seemed to prevail more among the rough- 

 chaffed wheats, than others, and, in this parish, more especially 

 in some fields of the variety called white -tunstall. At one time it 

 appeared likely that these fields would be seriously injured by it, 

 but some warm sunny weather coming on, the Red-rag lost ground, 

 and I observed that the sori, or spots from whence the spores exuded, 

 turned deep-brown. This disease is not so injurious as the true 

 mildew ; but although I shall speak of the latter as if it were 

 produced by a distinct species of fungus, and in compliance with 

 the present opinions of most systematic botanists, still I am very 

 much inclined to think that both diseases are occasioned by the 

 same fungus, under different forms or states of fructification. 

 I did not witness the fact, but was told that the reapers had 

 noticed several patches of mildew among the white-tunstall alluded 

 to above. I much regret that I did not see them. My chief 

 reason for supposing it probable that rust may result from a par- 

 ticular form of fructification in the same fungus which produces 



