How to Make Your Own Spray to Prevent Black Spot on Roses

Black spot (Diplocarpon rosae) is a fungus that attacks rose bushes. Black spot spores spread through water, and rain and humidity make black spot worse. Always water your roses at the bottom of the plant. As the name says, it causes black spots on the leaves. Black Spot also causes the leaves to turn yellow and fall off, leaving you with leafless shoots.

1 1/2 tbsp. baking soda
3 tbsp. horticultural oil

Instructions

- 1
  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).
- 2
  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.
- 3
  Every time you spray your rose bushes, you need to mix these ingredients. The mixture cannot be stored because the ingredients lose their effectiveness.
- 4
  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.

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