BLACK STEM liVST OF OATS. 65 



Liability of different varieties to this rust. — But litth>- iulbrmution 

 exists as to the liability of different varieties of oats to rust iu this 

 eountry >>ased on any case in wliioli it was detiuitely known that the 

 stem rust was the chief one under observation. In the season of 1894 

 the writer assisted Prof. J. IJ. Shepperd in grading" the rustiuess of 

 varieties of oats grown at the North Dakota Agricultural Experiment 

 Station, F. graminis being tlie dominant rust on oats that season, not 

 only there but also throughout the North and West. The following- 

 season Prof. H. L. Bolley, of that station, graded the rustiness of the 

 same varieties, and in a recent letter received from him he states that 

 P. (jramlniH was the chief rust present that year, but that the presence 

 of P. coronata accounts for the small percentages of rust noted for cer- 

 tain varieties. The results of the two years' grading were reported by 

 Professor Shepperd iu a bulletin issued March, 189G (04, pp. 38-40). 

 The i^erceutages for the same varieties for the two seasons correspond 

 quite well as a rule, antl show almost entire freedom from rust in the 

 case of Early White Kussian, Fentons Rust Proof, Tartarian, and Great 

 Northern, and an abundance of rust on Giant Yellow, American White, 

 Badger (^ueeu, and North Star. 



This rust occurred to a small extent on the varieties of oats in the 

 field experiments at Salina, but on account of its late appearance and 

 the great abundance of the crown rust it was impracticable to grade 

 the amounts on the different varieties. 



In Australia, where so much has been written on rust-resistaut 

 wheats, apparently no attention has been given to rust-resistant oats, 

 probably for the reason that oat rust is of little economic importance in 

 that country. In 1803 Eriksson made some observations (31, pp. 348- 

 350) on rust liability of varieties of oats in Sweden, es])ecially as regards 

 the black stem rust, and concluded that iu Sweden there is no particu- 

 lar difference in the susceptibility of different sorts of oats to this rust-. 



Damage.— The damage which this rust causes to oats iu this country 

 is even greater than that produced by the form occurring on wheat. 

 In fact almost every year thousands of acres are totally destroyed in 

 some portions of the country by this parasite, the damage being great- 

 est north of the thirty-seventh degree of north latitude and east of the 

 ninety-fifth degree of west longitude. According to Eriksson (31, p. 

 386), it is also very destructive at times in Sweden, the damage to oats 

 in that country from this cause in 1889 amounting to IG million crowns 

 (about 4.^ million dollars). 



MAIZE BUST. 



{Puccinia, sorghi Schw.). 



Physiological relations, — The fact that the maize rust bears some mor- 

 phological resemblance to the rusts of certain grasses, particularly to 

 P. graminis of wheat and oats, led the writer to suspect that it might 

 ' 21704— No. IG 5 



