88 James G. Horsfall 



The disease 



Since the name timothy rust is adequate for the purpose, it is adopted 

 in this bulletin. 



History and range 



Settegast in 1864 remarked that timothy is not affected with rust when 

 growing in juxtaposition to barberries (1864:384). In the United States, 

 Trelease (1885:131) first recorded timothy rust in 1885. It was not 

 reported again in America until 1906 when it " became epidemic in the 

 experimental plats at the Arlington Experimental Farm " (Johnson, 

 1911:7). In 1907 it was first discovered in New York in the Cornell 

 timothy plantings at Ithaca. It was abundant the same year in Penn- 

 sylvania and Indiana (Webber, 1912:352). From that time the fungus 

 has been found in many places in the United States and Canada. Mercer 

 (1914:20) remarks that " the spreading and destructiveness of the disease 

 has been little short of phenomenal." 



Arthur (1920:297) gives the distribution of this rust from Nova Scotia 

 and Maine to Louisiana and from Virginia to Washington, California, and 

 Manitoba. The disease appears to be ubiquitous in the United States 

 and Canada. The Sydows (1904:785) report the disease in Europe from 

 Germany, Austria, Denmark, and Sweden. Stapledon and others (1922: 

 16) find it in Wales, and Madame Teterevnikova (1927) states that it 

 occurs in a severe form on timothy in Russia. 



E Genomic importance 



Timothy rust is a destructive disease. Webber (1912:352) in an ear'y 

 report on the disease in New York State says, " Observations made every 

 year for the last five years in various parts of the State have shown that 

 rust is the most serious disease affecting timothy." During 1926 to 1928, 

 however, this condition did not obtain in New York. It may be that 

 timothy was more subject to the disease when it first became epiphytotic 

 during the first decade of this century. At any rate, it was far over- 

 shadowed by the Cercospora leaf spot in 1928. Miss Sampson reports a 

 great reduction in seed yield in Wales as a result of rust. She says that 

 in 1922 the weight of 1000 seeds was reduced from 0.39 to 0.19 gram and 

 in 1923 the weight of an equal number of seeds was reduced from 0.43 to 

 0.31 gram. Johnson and Haskell (1920:75) report an estimated loss of 

 2 per cent of the crop in Minnesota in 1919. Cook and Helyar (1915:6) 

 note that " the timothy rust is also occasionally found in New Jersey but 

 cannot be considered of importance." 



Symptomatology 



Symptoms do not play a very important part in the diagnosis of this 

 disease. The leaves may be of a nondescript yellow color as they are killed 



