on the four cereals. (24) An American has been foremost in 

 continuing this work with Puccinia graminis. In 1926 Stakman 

 distinguished some fifty "physiologic forms" of Puccinia grami- 

 nis tritici in the United States. (57) Work of the last ten years 

 has raised the number to nearly one hundred fifty. These results 

 are the outcome of an attempt to breed rust-resistant varieties 

 of wheat. (29) It will be readily seen that this great number of 

 biologic species of the rust has added difficulties to the solution 

 of that problem. 



Rust-resistant varieties have been much more successfully 

 produced against the less highly specialized asparagus rust 

 which we find in Norton on roadside escapes from gardens. The 

 development of a resistant asparagus was the work of the United 

 States Department of Agriculture in cooperation with the 

 Massachusetts Agricultural Experiment Station. Asparagus 

 varieties from all parts of the world were grown at Concord, 

 Massachusetts. A cross between English and American strains 

 produced the now world-famous Washington strains. (59, 60) 

 Agricultural handbooks now advise the control of asparagus 

 rust by the planting of rust-resistant strains; gardener's cata- 

 logues list Martha and Mary Washington asparagus. 



Asparagus rust was described by de Candolle in 1805 (16) 

 but the first record of its occurrence in America was in a report 

 by Halsted in 1896 of a rust epidemic in New Jersey, Delaware, 

 Long Island and New England. (38) This destruction of the 

 eastern crop gave California a chance to develop the asparagus 

 culture but the rust travelled westward and in seven years had 

 reached California. The rust produces all spore forms on the one 

 host but the summer uredospores are thought to be chiefly 

 responsible for the spread of infection. Blown by moist winds 

 they could colonize nearby fields, and so, slowly but independ- 

 ently, travel across the continent. The picture is graphically 

 drawn by R. E. Smith. "When one sees the cloud of dust which 

 arises from rust plants when disturbed, coloring . . , anything 

 passing through the field a deep red color, flying away in the 

 wind like smoke, covering the berries which contain the seed, 

 covering and coloring the ground from which roots are dug for 

 sale, and reflects that each minute particle of this dust is a rust 

 spore, it would seem that the spread of the disease must occur 

 in many ways through the agency of these summer spores. 



