44 MASS. EXPERIMENT STATION BULLETIN 183. 



Method. — Glass slides were sprayed with the fungicide to be tested and per- 

 mitted to dry for varying periods of time. Then spores of the fungus in a drop of 

 water were transferred to the center of the sprayed slide, which was then kept 

 in a moist chamber for twenty-four hours. Checks on unsprayed slides were 

 always made at the same time. Percentages of germination were counted at the 

 end of twenty-four hours, and observations were taken for several days to see if 

 there was any further development; but none of the results in these tests were 

 modified by later observations. When a dry fungicide was used it was dusted on 

 to the slide without water. All checks in these tests germinated over 95 per cent. 



Lime-sulfur. ■ — Concentrations of 1-10, 1-30 and 1-50 commercial 

 lime-sulfur solution were used. The 1-50 concentration proved to be 

 useless from the start. The 1-30 seemed to check germination at first, 

 but after it had been on the slide four or five days over 50 per cent, of 

 the spores germinated. The 1-10 concentration entirely prevented 

 germination when fresh, but after a week the control was erratic, with 

 over 50 per cent, germination on some of the slides. Commercial lime- 

 sulfur seems to be useless for control of this fungus. 



Dry Sulfur Flour. — Slides were very heavily dusted and the germina- 

 tion tests made at about 25° C. The presence of the sulfur had no effect 

 whatever on the spores. They germinated just as well as the checks. 

 Dry sulfur appears to be even less effective than the lime-sulfur. 



Ammoniacal Copper Carbonate. — This fungicide prevented germina- 

 tion twenty-four hours after being dried, but when tried a week later was 

 only 25 per cent, efficient. This would hardly be a safe fungicide. 



Lime. — Milk of lime sprayed on the slides from an atomizer pre- 

 vented germination from the first, and was just as effective as Bordeaux. 

 Milk of lime is not suitable for dipping cuttings. The lime test was 

 made with a different end in view. 



Bordeaux Mixture. — This fungicide was made up at a strength of 

 4-4-50. Germination tests were made every day for twenty-one days 

 after the slides were sprayed. No germination occurred in any of these 

 tests. These fungicidal tests clearly indicate Bordeaux mixture as the 

 most suitable solution for dipping cuttings. 



Treatment of the Walks in the House. 

 Undoubtedly the walks between the benches of a house which has 

 previously grown diseased roses are infested with the pathogene. One 

 could easily think of a great many ways in which small particles of soil 

 from the walks could be carried into the benches. It is therefore necessary 

 either to keep the fungus killed out of the surface of the walks by repeated 

 applications of some fungicide or to cover the walks with some sub- 

 stance which will be a barrier through which it cannot pass up to the 

 benches. In the beginning of this investigation the walks were kept 

 sterile by frequent applications of formaldehyde. This proved unsatis- 

 factory because the fumes of formaldehyde often injure the roses, pro- 

 ducing dead spots on the leaves. This was abandoned and a search 



