Family Liliaceae 281 



made up of the teleuto or winter spores of the fungus. 

 In old asparagus fields, rust may appear early in the 

 season. In this case instead of rusty brown son 

 there appear on the main stems and branches, but 

 not on the needles, numerous bright cup-shaped 

 bodies, containing the aecidial or spring spores. 

 This form occurs about May but disappears in June 

 or July. This stage is immediately followed by red 

 pustules which contain the uredo or summer spores. 

 Later in August and September, and as already 

 stated the teleutospores appear. The latter help 

 to carry the fungus over winter and unfavorable 

 conditions. The effect of asparagus rust is an in- 

 direct weakening of the crowns of the plant. Affected 

 tips fail to store up the necessary starches and sugars 

 for the underground crowns. The latter being un- 

 der-fed become weak, soft, and subject to the attacks 

 of various, soil-inhabiting parasites. 



The Organism. The life history of Puccinia as- 

 paragi has been carefully worked out by Smith x and 

 others. The mycelium of the fungus is long and 

 narrow, extensively branched, deriving its food by 

 means of suckers or haustoria which penetrate the 

 cells of the host. The aecidiospores are formed in 

 chains, coming up from the mass of mycelium at the 

 base of the cup (fig. 52 b). The uredospores (fig. 

 52 c) are dark in color and are borne singly in the 

 uredo pustules. Both the aecidio- and uredospores 

 are one celled, and both germinate by means of a germ 

 tube which penetrates the host. The black rust or 



1 Smith, R. E., California Agr. Expt. Sta. Bui. 165 : 5-99, 1905. 



