III. COMBATING CARNATION RUST.* 



Summary. 



(1) The majority of cairnation growers still consider rust one 

 of the most serious enemies to carnation culture, but it is not 

 dreaded nearly so much as it was three years ago. 



(2) Carnation rust is not localized at the point where the pus- 

 tule appears, but may be found in all parts of the plant. 



(3) Rust spores are not carried from one part of the plant to 

 another by the circulation. 



(4) Rust cannot rise spontaneously. The theory of spontane- 

 ous generation is exploded. 



(5) The rusts found on various weeds are not the same as car- 

 nation rust. 



(G) There have been made scarcely any properly conducted 

 tests of fungicides for carnation rust. 



(7) Some of the fungicides which have been most commonly 

 recommended are: Bordeaux mixture, Fostite, potassium sul- 

 phide, carbolic acid, copper sulphate and copper sulphate in 

 ammonia. The reports on these fungicides are conflicting. 



(8) Tests of spore-germination in copper sulphate solutions in- 

 dicate that 1-1000 solution is much too weak to prevent rust. 

 Spores germinated readily in 1-500 solution, and there was some 

 germiaation in 1-300 solution. 



(0) One to forty-five appears to be the strongest salt solution in 

 which rust spores can germinate. 



(10) Spore-germination tests show that carnation rust spores 

 are remarkably susceptible to the action of potassium sulphide. 

 A 1-3000 solution entirely prevented germination 



(11) Cuttings soaked in copper sulphate solutions were much 

 injured. One-half hour in 1-2000 solution produced decided in- 

 jury. 



(12) Cuttings soaked in salt solution 1-20 were much injured; 

 1-40 solution apparently did no harm. 



♦Published also as Bulletin No. 100. 



