Mix the following ingredients in a bucket: 1 gallon distilled water, 1 1/2 tbsp. baking soda and 3 tbsp. horticultural oil (available in garden centers and online).
Pour the mixture into a spray bottle that has a fine mist. Spray your roses every week or every other week after the budbreak. Make sure to spray the entire plant including the undersides of the leaves. If it rains spray them when the rose bushes have dried.
Every time you spray your rose bushes, you need to mix these ingredients. The mixture cannot be stored because the ingredients lose their effectiveness.
Be sure to spray in the morning because if you spray the rose bushes when the sun is hot and blazing, you will damage the leaves. Do not spray at night because your mixture will not dry.