REPORT OF THE BOTANIST. 



A PARASITE UPON CAENATION RUST. 



Frederick H. Blodgett. 



SUMMARY. 



The growers of carnations in America have been tronbled since 

 1891 with a disease known as rust, TJromyces caryophiiUlnus (S.) 

 Schroet. No marked success has followed the numerous attempts 

 to check its development. Recently a natural check was noticed 

 infesting the pustules of rust; this was the fungus, Darluca filum 

 (Biy.) Cast. Possibly some benefit may be derived from artificially 

 introducing this fungus into carnation houses, but it is not suffi- 

 ciently abundant to be of great assistance in natural conditions. 



INTRODUCTION. 



The carnation industry employs many men and a large amount 

 of capital and tends to concentrate about the large cities. Many 

 varieties are grown, some healthy and robust, others diseased and 

 sickly when (Similarly treated. One of the most common diseases 

 is the rust, which manifests itself by producing blisters upon the 

 leaves and stems from which a tine orange-brown powder escapes. 

 The powder is formed of the spores of the fungus Vromyces cary- 

 opJiyUiiius uS.) Schroet. There is no satisfactory method of con- 

 trolling the rust when once introduced. 



On many rusts there is present in the pustules a fungus which 

 attacks the rust plant and lives upon it as the rust lives upon the 

 host. This fungus, Darluca filiim (Biv.) Cast., has been recently 



♦Reprint of Bulletin No. 175. 



