490 Journal of Agricultural Research voi. x, No. 9 



is snread to the wheat fields from the barberry bushes or from occasional protected 

 spots, as beneath ice, by the aid of the native grasses. 



The experience of the writers does not agree entirely with that of 

 Pritchard. As mentioned previously, the writers are in doubt as to the 

 importance of the overwintering of the uredinial stage on grasses. But 

 observations made in Minnesota for the past few years indicate that 

 barberries may be important, at least locally. 



In 1 91 4 numerous well-developed aecia of P. graminis secalis were 

 found on barberry growing near Lake Minnetonka, Minn., as early as 

 May 17. Successful infection was repeatedly obtained on rye and 

 barley, but not on wheat or oats. At this time there was no rust on 

 barley or rye in the region, but Agropyron repens near the barberries 

 soon became heavily rusted. New aecia continued to be developed at 

 irregular intervals until July 10 and possibly longer. Pycnia began to 

 appear on barberries on University Farm, St. Paul, on May 18 and by 

 May 22 aecia had formed. Wheat, oats, barley, and rye were inoculated 

 with the aeciospores on May 23, and wheat and barley became infected, 

 while oats and rye did not, showing that the rust was P. graminis tritici. 

 iEcia developed in great abundance on another group of barberries on 

 University Farm about May 20. By June 9 volunteer rye, Agropyron 

 repens, and Hordeum jubatum near these barberries had become very 

 severely rusted. Inoculations made with both aeciospores and the 

 urediniospores showed that both P. graminis secalis and P. graminis 

 tritici were present. Most of the rust was P. graminis secalis. At this 

 time grasses and wheat at some distance from the barberries were not 

 at all rusted. Winter wheat near barberries was beginning to rust. 



In 1 91 5 viable aeciospores were obtained at University Farm on May 

 8. These proved to be P. graminis tritici. Successive crops of aecia 

 were produced until about July i, and, as in the previous year, both 

 near these barberries and others bearing aecia of P. graminis secalis, 

 grasses and cereals, when these were growing near, rusted severely while 

 those at some distance remained free for about a month, when the rust 

 began to appear quite generally on grasses. On July 10, at Dickinson, 

 N. Dak., Agropyron repens, A. ienerum, and Hordeum juhaium were 

 found very badly rusted near a group of barberries, while the same 

 grasses and wheat half a mile away were just beginning to rust. On 

 July 12, at Jamestown, N. Dak., Hordeum jubatum was found badly 

 rusted near a field of Marquis wheat which was just beginning to rust 

 slightly. A few miles away A. smithii was literally covered with uredini- 

 ospores; in fact, the ground was red with them, and a field of wheat 

 next to the grass was just beginning to rust. No barberries were seen, 

 because lack of time prevented a search on farmsteads near by. The 

 observations merely emphasize the fact that grasses do sometimes rust 

 before cereals, and that the rust may spread from them to the cereals. 



