New York Agricultukal Experiment Station. 125 



How and when the rust was introduced into this country is not 

 known. It is possible that it was imported from Europe on plants 

 or with a seed' a number of years prior to its discovery and, like 

 the gipsy moth, required several years to become well enough 

 established to be noticed. Although it ia not known for how 

 long a period the spores of the rust can withstand the drying 

 effect of the wind, there is little doubt that the latter is one of 

 the principal agents in distributing the rust over the country. It 

 has certainly spread over a larger extent of territory during the 

 past few years than would have been possible through distribu- 

 tion of the spores on asparagus plants and seeds, 



DESCRIPTION. 



Asparagus rust has been frequently described during the past 

 few years; and its wide distribution makes it a well-known dis- 

 ease; yet it is deemed best to repeat briefly some of its charac- 

 teristics as a basis for clear understanding of the experimental 

 work herein reported. 



It is a parasitic plant, or fungus, growing within the asparagus 

 and absorbing the juices which should go to build up the tissues 

 of the latter. The portion of the rust plant which we see and 

 which gives it its name, is simply the spores, or seeds, of the 

 fungus. These are formed beneath the epidermis, or bark, of the 

 asparagus plant, causing this epidermis to lift and form pustules 

 which, in two stages, produce slits or rifts. All are called sori. 

 (See Plates X and XI, Figs. 1.) 



The rust has three rather distinct stages or forms of growth. 

 All three can occur on the same plant and frequently more than 

 one form occurs at the same time. 



Mcid/ial stage. — The first form, known as the eDcidial or " clus- 

 ter-cup " stage (see Plate X, Fig. 1), and sometimes called the 

 *^ spring form " of the rust, is not usually distinguished from the 

 second stage by growers of asparagus. It makes its appearance 



•p. H. Rolfs has reported finding the rust spores adhering to the aspara- 

 gus seed. S. 0. Agr. Exp. Sta. Rept. 1899, p. 17. 



