194 DISEASES OF ECONOMIC PLANTS 



VEGETABLE AND FIELD CROPS 



ASPARAGUS 



Rust (Pucdnia Asparagi DC). — The asparagus rust, 

 though observed in Europe as early as 1805, was not 

 noted in epidemic form in the United States until 1896, 

 when it was recorded by Halsted^ as occurring in sev- 

 eral New England States. In 1897, though it had extended 

 to South Carolina and to some extent westward, the interior 

 and western part of the United States seemed still free 

 from it. In 1898 it was first found in Michigan; in 

 1899 in Illinois, Ohio,, and Kansas; in 1900 in Dakota, 

 Nebraska, and Texas, completing its westward march into 

 California in 1900 or 1901. It is now known in every state 

 where asparagus is grown. 



The rust usually first attracts attention by its effect 

 upon the green tops which redden under the disease, this 

 symptom appearing at any time after blossoming or com- 

 ing to leaf. Diseased areas in the field enlarge rapidly, and 

 soon the affected leaves yellow and fall, leaving the bare, 

 dead stalks. Close examination of the diseased regions 

 in the field shows that the twigs and leaves 1)ear many small 

 blisters (sori), consisting of the raised skin of the plant. 

 Under this skin is a mass of powder nearly the color of iron 

 rust. In early stages of attack these bhsters are few and 

 scattered, but they rapidly increase in number. When 

 young, the skin covering the sori is unbroken; later it rup- 

 tures, setting loose the rusty powdery mass of spores be- 



1 Halsted, B. D., N.J. Agr. Exp. Sta. Rpt. 1893, p. 329, and N.J. Agr. 

 Exp. Sta. Bui. 129, 1898. 



