128 TWENTY-FIFTH ANNIVERSARY REPORT. 
to the florists indicated a general desire for an investigation of 
carnation rust. Although this disease had but recently made its 
appearance in the United States it was already widespread, and 
florists were much alarmed over it. 
The Station investigations*® included tests of spore germination 
in fungicides, soaking the cuttings in fungicides, and spraying ex- 
periments. The spore germination tests brought out the fact that, 
as a preventive of germination, potassium sulphide is mu¢h more 
efficient than copper sulphate. Potassium sulphide solution, strength 
I :3000, completely prevented germination; whereas, copper sulphate 
solution ten times as strong did not wholly prevent germination. 
The object of the experiments on the soaking of cuttings was to 
find a method of killing the fungus mycelium within the tissues 
without injury to the cuttings. The results indicated that potas- 
sium sulphide is better adapted to this purpose than copper sulphate 
or common salt, but definite conclusions were not reached. 
In the spraying experiments weekly applications of copper sul- 
phate solution (2 lbs. to 45 gals.) brought 58 per ct. of the plants 
through to “lifting time” free from rust, while untreated plants 
under parallel conditions were ail rusty. Potassium sulphide solu- 
tion (1 oz. to I gal.) gave nearly as good results as copper sulphate, — 
but bordeaux mixture (1 to 7% formula) and salt solution (8 Ibs. 
to 45 gals.) proved complete failures. None of the solutions in- 
jured the plants. 
In. the light of subsequent events it must be admitted that this 
work on carnation rust was not productive of any important re- 
sults so far as the practical control of the disease is concerned. 
Although copper sulphate and potassium sulphide sprays are fairly 
efficient, as shown by the experiments, few florists now use either 
to any great extent. At the present time, carnation rust is com- 
bated chiefly by giving careful attention to the temperature and 
moisture in the greenhouse and by the use of rust-resistant varities. 
In 1897 it was shown by experiment that common salt solution 
applied to the foliage of carnations or to the soil in which they 
are grown will neither prevent rust nor give the plants a more 
vigorous growth. The popular opinion that common salt has value 
in the culture of carnations is probably not founded on fact.*? 
In 1899 a brief. study was made of an unusual leaf spot disease 
‘3 ly odhiyces caryophyllinus (Schrank) Schroet. 
“Bul. 100 (1896); same in Rpt. 15:461-495. 
* Bul. 138:635-636 (1897) ; same in Rpt. 16:423-425. 
Wee 
