New York Agricultural Experimext Station. l-ii) 



that there was an actual iuirease in yield of 14.5 per ct. from 



sjjrajing. 



THE PARASITIC DARLUCA. 



In 1898 Dr. Halsted-^ found a fungus known as Darluca filum 

 Cast., which is a parasite upon many rusts, attacking asparagus 

 rust. 



This parasitic fungus has been so prevalent during the past two 

 years that most growers of asparagus are familiar with it. Its 

 abundance and the rapidity with which it spreads upon the uredo 

 or summer stage of the rust has led others besides growers to 

 anticipate remarkable benefitg from its attacks on the rust. 



During the past summer (1900) Darluca attacked the secidial 

 stage of the rust about June 10. Ten days later all the rusted 

 asparagus stalks were covered with the Darluoa. Notwithstand- 

 ing the above condition, there was a severe outbreak of the sum- 

 mer stage of the rust on seedling beds about July 1, which was 

 immediately followed by the Darluoa. About the middle of 

 August as severe an outbreak of the summer stage of the rust 

 as has ever occurred in previous years appeared on the cutting 

 beds. This in turn was followed by the Darluca. The same con- 

 ditions were repeated again in September on the late watery 

 shoots of asparagus. All of these attacks of the Darluca were 

 followed by the formation of an abundance of the teleuto spores 

 or winter stage of the rust. 



Cross sections of the sori or rifts of the summer stage of the 

 rust frequently show the condition illustrated in Fig. 2, Plate XI, 

 that is, the sori will be filled with the uredo or summer spores 

 w^hile beneath them a layer of the winter spores will be fornjing. 

 We have even found sori in which the uredospores were appar- 

 ently destroyed by Darluca while at the bottom of the sorus a 

 layer of evidently healthy winter spores would be found. 



The formation of the winter spores of the rust on the same 

 plant where the uredo stage had been attacked by Darluca, com- 

 bined with the conditions shown in Fig. 2, Plate XI, all indicate 

 that the Darluca attacks the spores of only the iEcidial and uredo 



"N. J. Agr. Exp. Stas. Bui. 129, p. 15. 



