New YorK AGRICULTURAL 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 is 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 
hag 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. AJl 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. 
Aicidial stage.—The first form, known as the ecidial 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. 8. 6. Agr. Exp. Sta. Rept. 1899, p. 17. 
