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Treatment: Choose black spot resistant varieties and be meticulous about sanitation. Water the roots of the rose, avoiding the foliage. Water in the morning, so that splashed leaves have time to dry off. If Black Spot is an annual problem, try a dormant spray of lime sulfur at the end of the season and again in early summer. Once Black Spot appears, it is hard to stop. Neem oil and Sprays containing Potassium bicarbonate are somewhat effective.

There are a few home remedies that have met with some success and are worth trying, especially for those that really do prefer organic garden methods. One is a solution made with baking soda: dissolve 1 teaspoon baking soda in a quart of water, add a few drops of liquid soap to the mix to help it cling better to the foliage, spray infected plants thoroughly. Another unusual remedy for fighting fungal diseases is manure tea. This formulation fights blackspot, as well as mildew and rust, while providing foliar nutrition. Place one gallon of well-composted manure in a 5-gallon bucket and fill with water. Stir the mixture well and let sit in a warm place for three days. Strain the mixture through a cheesecloth or mesh and use the resulting tea to spray disease affected plants (the solids left behind can be applied around the base of the plants as added fertilizer).

While plants are dormant in spring, spray thoroughly with fungicidal soap and wettable sulphur (both readily available at the local plant nursery). Sulphur is actually a historical remedy used or hundreds of years by farmers for their crops. It definitely has a place in the chemical-free garden. Fungal spores cannot germinate in the sulphur film and thus cannot get a chance to attack the plant. To be effective the sulphur must be on the plant and leaves before the spores land on them. Sulphur washes off in rain and so must be reapplied repeatedly. The product is sold in powder or liquid form and also works well against mildew and rust. Other preventative measures include keeping the leaves dry when watering (try soaker hoses or drip irrigation methods), water in the morning so that foliage has a chance to dry off throughout the day and pruning plants to improve air circulation. Also spacing the plants well when planting will insure good air circulation. It is recommended that hybrid teas and smaller rose bushes be spaced 3 feet apart and larger rose bushes be spaced 4 feet apart from one another.