CARNATION WILT DISEASES 15 



value after 7 to 10 dajs from the date of preparation. The spores of the car- 

 nation rust fungus seemed to be much more tolerant of potassium permanganate, 

 but immersion of sori longer than 30 minutes and for as long as 48 hours de- 

 stroyed the power of the spores to germinate. 



When King Cardinal cuttings were dipped in a water suspension of spores of 

 theUromyces rust fungus and then immersed in water for 15 hours, 32.8 percent 

 showed rust pustules after growing in the sand for 24 days. In contrast, only 

 3.2 percent of the cuttings immersed in potassium permanganate 1-1,000 for 45 

 minutes and kept moist over night showed rust. Immersed in potassium per- 

 manganate for 15 hours, 1.2 percent of the cuttings showed rust; immersed in 

 water for 45 minutes and kept moist over night, 72.8 percent of them were 

 infected. In other tests the amount of disease was determined from a count of 

 the infections in the blades and stems. Infection at the base of the stem was 

 indicated by decay or discoloration or both. This was regarded as a separate 

 infection and was added to the number of infections found elsewhere on the 

 cuttings to obtain the total. The value of potassium permanganate as a dis- 

 infectant is shown in Tables 3, 4, and 7. Beginning with the earliest tests con- 

 ducted in 1931, the results with potassium permanganate have been outstanding. 



Malachite green was consistently toxic in dilutions up to 1-40,000 and strong 

 effect was shown in a range of 1-20,000 to 1-40,000. At weaker dilutions con- 

 siderable germination was noted. The consistent fungicidal effect of malachite 

 green at these weak dilutions represented a distinct contrast to that obtained 

 from potassium permanganate. The toxic effect of malachite green 1-25,000 to 

 the spores of the rust fungus was more rapid and complete than that of potassium 

 permanganate 1-1,000. Howard (34) found that malachite green at great dilu- 

 tions is strongly fungicidal to the spores of Alternaria solani (Ell. and Mart.) 

 Jones and Grout. A similar effect upon Alternaria dianthi is shown here. Never- 

 theless, the control of disease among artificially inoculated cuttings immersed in 

 malachite green solution has not been satisfactory (Tables 7, 8, 9). More study 

 is needed. 



Table 3. Effect of Chemical Solutions on Rooting of Boston Ward 

 Carnation Cuttings and Control of Alternaria. 



Treatment (5 Minutes) Number of Percent Number Infections 



Cuttings Rooted Per 100 Cuttings 



A 

 Mercuric Bichloride 1-1,000 

 Uspulun 2.3 gms.- 1,000 

 Potassium Permanganate 1-1,000 

 Bordeaux 4-4-50 

 No Treatment 



B 

 Potassium Permanganate 1-1,000 

 Uspulun 2.3 gms.-l,000 

 Bordeaux 4-4-50 

 No Treatment 



C 



Potassium Permanganate 1-1,000 

 Bordeaux 4-4-50 

 No Treatment 



