Black Spot on Roses

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Posted on 05/01/2022

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Every gardener who raises roses will at some point face black spot. Whether you grow tree roses, shrub roses or cutting roses, it makes no difference — black spot is one of the most common problems faced by roses and their caregivers. Everywhere roses are grown, black spot also survives. But the good news is that there are ways to protect your roses when it happens!

What Is Black Spot?

Black spot is a fungal disease that looks just like its name implies. Black spots form on the foliage and, if not treated, will spread to all the foliage and even the stems of your colorful roses. Leaves affected by black spot will turn yellow and fall off the rose plant. 

It’s important to treat your infected plants immediately. If left untreated, your rose can become completely infected and lose all the leaves and flowers. Not only is this unsightly, but the plant will be weakened, stressed and vulnerable, and may not survive.

fungal rose with black spots

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This fungus loves moist and humid conditions. The prime season to see black spot is on cool, wet spring days and nights. While some fungus spores spread in the wind, black spot moves with the help of water. 

Black spot seems to come out of nowhere. One day your roses look totally healthy and the next you see the telltale spots. Remove any leaves that are infected immediately. They won’t survive anyway, and by removing those leaves, you may prevent the fungus from spreading to other parts of your plant or even neighboring plants. 

Just remember: Throw the infected leaves in the trash. You do not want to add them to the compost or leave them in the garden bed. Remember to wash your hands well after you handle your infected rose plants so you don’t accidentally spread the fungus.

How to Treat Back Spot Infected Roses

Your rose bush can be treated to easily stop the black spot. Stop black spot when it is discovered with a product called Bonide Copper Fungicide that you spray on your rose bushes to kill this fungus. 

As mentioned earlier, the leaves affected can’t be saved but you will minimize the damage. Bonide Copper Fungicide is an all-natural product that is safe to use on roses, fruits, vegetables and other flowers.

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How to Prevent Black Spot from Occurring 

Practicing good garden hygiene is an essential part of black spot prevention. Overhead watering, in most cases, should always be avoided. As mentioned earlier, this fungus loves damp moist conditions and overhead watering will wet the leaves and give black spot the perfect growing conditions.  

Water early in the day so there is ample time for the sun to dry the plants. If you water at night, your plants will remain wet and vulnerable to black spot all night long. Always clean away any dead and fallen leaves from below your plants. A layer of mulch will prevent rain or watering to splash back on the foliage. 

Good pruning of dead and damaged canes, as well as helping to keep the center of the plant open to allow good air circulation, will help prevent black spot. Clean your pruners with a 10 percent bleach solution or alcohol between plants to prevent spreading the fungus spores to other plants.

Plant your roses in full sun to minimize the conditions that black spot can thrive in. There are also some roses that are bred to be disease-resistant. These include April Moon™, Moondance, Enchanted Evening and many, many more. Visit our selection of disease-resistant roses.

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Prevent black spot from getting a foothold in your rose garden by pretreating with the Bonide Copper Fungicide. Though this product is an effective treatment for plants that have been affected by black spot, it is also very effective at preventing the disease in the first place.

Another product that can help prevent black spot is Neem Oil. Neem Oil is derived from the seeds of the neem tree and is considered an organic fungicide and pesticide. Apply while your roses are still dormant to prevent black spot.

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Making Your Own Preventative

If you prefer to make your own preventative, try a baking soda spray. Mix one teaspoon baking soda to one quart of warm water. Add up to one teaspoon of liquid soap. The soap is used to help the mixture to adhere to the plant leaves, but it will need to be reapplied after it rains.

While black spot is very common, it is preventable and very treatable. By following these simple preventative measures and treatments, your roses will be as beautiful and healthy as you could wish.