Rose gardeners should stay continually vigilant, watching for signs of disease and insect infestation during the growing season. Because it can be difficult to combat issues once they begin, prevention and early detection are two keys to controlling problems. Planting disease-resistant and insect-resistant rose cultivars should reduce problems significantly. Apply sulphur powder to roses as a preventive measure to prevent fungal diseases and insect infestation on your roses.
Prepare the coffee can to use as a shaker for the sulphur powder. Use the nail to make three to five holes in the plastic lid of the coffee can, pounding the tip of the nail through the plastic with the hammer.
Place the sulphur powder into the coffee can and place the prepared lid onto the can.
Shake the sulphur powder generously over the rose foliage and the mulch on the soil, beginning early in the season when the plant first leaves dormancy. Cover all stems and leaves with a thin and even coat of sulphur powder.
Reapply the sulphur powder once each week or after rain. In order for the sulphur powder to remain effective on the rose foliage, you must keep a layer of sulphur covering the plant.
Stop applying the sulphur powder when the temperature begins approaching 26.7 degrees Celsius. Sulphur can create a damaging phytotoxic condition on foliage with the addition of warm temperatures and sun on the roses.
Some gardeners prefer mixing sulphur powder with water and spraying the mixture onto roses. Mix about 2 tbsp sulphur powder with 1 gallon of cool water. Spray the mixture over rose foliage evenly to coat it. Repeat the application every five to 10 days or after a rainfall.