A certain experimental fungicide causes no harm to garden plants, though only if it is diluted at least to ten parts water to one part fungicide  Moreover, this fungicide is known to be so effective against powdery mildew that it has the capacity to eliminate it completely from rose plants
Thus this fungicide, as long as it is sufficiently diluted, provides a means of eliminating powdery mildew from rose plants that involves no risk of harming the plants
The effectiveness of the fungicide does not depend on its being more concentrated than one part in ten parts of water.