Sulphur in different forms is the great antidote for fungus, and our chief rose enemy, the mildew, is a fungus. The flour of sulphur is often dusted on the plants. This is perhaps the least useful method, and sulphur should never be allowed to reach the soil. It is sometimes sprinkled on the pipes, and sometimes placed in shallow pans and placed where the rays of the sun will strike it, as when at a high temperature it gives off its fumes that destroy the spores of the fungus.
I think it is most beneficial, most easily applied, and the least harmful to the plants when it is mixed with linseed oil and painted on the pipes. Don't overdo it. Where there are eight or ten hot-water pipes, or twenty small steam pipes, paint the upper surface of one pipe; that will be sufficient. We think the oil does some good with the sulphur. This is an excellent preventive of mildew.
Sulphur is sometimes burned on hot bricks or an old shovel made red hot. I have done it and it is of course a very effective way of applying the deadly fumes, but you must be very careful and directly the odor of sulphur is plainly noted you must move on a few yards. When the carnation rust was at its worst a few years ago we burned a great deal of sulphur in the houses when they were entirely empty in the month of August. We made it strong enough to kill a Kilkenny cat and trust it killed all the spores and germs of the rust and other fungous diseases.
Sulphide of potassium, known as liver of sulphur, is a good preventive and possibly a cure for mildew. I have used it dissolved in water and then mixed with clay till it was the consistency of molasses, and on the pipes put a dab of the paint here and there, say every three feet. It is stronger than the common sulphur. Or the roses can be syringed with it; one pound in fifty gallons of water.