ITT 



Rust of Hamilton and Marion Counties, Indiana, 



By Guy West Wilson. 



Tlie prosi^'iit catalogue of Urcdivnles is based chiefly upon a c(7llection 

 of thirty-eight species made in th(! soutlieni ])art of Hamilton and the 

 northern part of Marion counties between the 3d of August and the 2d of 

 September of the present season. The hosts number forty-four, of which 

 Aster paniciilaivs and Arena sativa were the most prolific, the former 

 harboring three and the latter two species. I'reviously Init two species, 

 (lymnoconia interstitialis and Dicaeonia canaliculata, had been collected 

 in this region. The foi'mer did not reappear in this collection, thus making 

 the total number of species to date thirty-nine. This, however, can be 

 regarded merely as a preliminary catalogue, as the collecting season was 

 too short and the time which could be devoted to the work too limited to 

 make an exhaustive collection. A number of other species have been 

 observed in previous years, but as no specimens were collected they are 

 not included in the present list. Careful collecting in this region would 

 probably double the number of species and would certainly greatly ex- 

 tend the list of hosts for those already collected, as the host plants of 

 forty-five other Indiana rusts as well as some thirty-five additional hosts 

 of those here enumerated occur in this region. 



Of the species catalogued, twelve may be classed as injurious, as their 

 hosts are cultivated plants. A few other species occur upon plants which 

 are cultivated elsewhere, and in such localities would be properly classed 

 as injurious, while in the present instance they might even be considered 

 beneficial species. Among the injurious species first place belongs to the 

 gi'ain rusts (Dicaeoma pocuUforme and D. rlmmnij, Avhich often seriously 

 reduce the yield of small grains. Of scarcely less importance is the black- 

 berry rust (Gymnoconia interstitialis), wliich was disastrously al)undant 

 in this region a half dozen years ago. So great was its ravages that a 

 considerable acreage of blackberries which were cultivated for market had 

 to be removed. The rust was not seen this season and was not abundant 

 last, so the fruitgrowers are again putting out blackberries.* The Carolina 

 poplar, which is used as a shade tree in towns, is sometimes seriously 



■••'Abundant on wild sps.of Rnhun in May, 1906. 

 12— A. OF Science. 



