Besides looking unsightly, black spot can seriously weaken the rose plant.
Black spot thrives during cool, moist weather.
Read on for information about black spot on roses, including symptoms and treatment.Want more gardening tips?
The Spruce / Marie Iannotti
Illustration: The Spruce / Melissa Ling
What Are the Symptoms of Black Spot?
What Does Black Spot Do?
Without leaves, they become stressed and susceptible to more problems.
Illustration: The Spruce / Melissa Ling
What Causes Black Spot on Roses?
Removing and destroying infected parts is essential.
Otherwise, your roses will get more black spots.
The Spruce / Christopher Lee Foto
Understanding the fungal disease’s life cycle is a crucial first step.
Existing spores overwinter on infected fallen leaves and stems, waiting for favorable conditions.
The spores germinate in spring and must be continuously wet for seven hours before germination occurs.
The Spruce / Christopher Lee Foto
The spores ultimately develop into fruiting bodies within the black lesions.
The fruiting bodies produce more spores that splash onto new tissue, spreading the disease.
Proper Lighting
Roses prefer a sunny location with well-draining soil and regular, weekly watering.
The Spruce / Ulyana Verbytska
Plant roses where they receive morning sun, which helps dry moisture from the leaves.
Full, all-day sun is best.
Good Air Flow
Provide good air circulation around and through your rose plants.
Do not plant your roses too close to other plants.
Proper Watering
Avoid getting the leaves wet while watering.
Consider installingdrip tape irrigationaround your roses.
Pruning
Cut back roses with black spot.
The disease starts spreading within 10 days of the first symptoms.Spores spread by water.
They remain on leaves and stems and reinfect whenever conditions are favorable.
Remove any infected leaves and always clean thoroughly each fall.
Remove and dispose of any remaining leaves when you do your dormantrose pruningin late winter or early spring.
Disinfect yourprunerswith a 10 percent bleach solution or alcohol between cuts.
Dispose of infected leaves and canes.
confirm to clean up fallen leaves and dispose of them properly.
Warning
Do not compost infected plant material, as the spores may potentially reinfect plants.
Mulch
Apply a thick layer ofmulcharound the plant’s base.
Ensure the mulch doesn’t contain rotting wood, sinceartillery fungusdevelops in a moist environment.
The treatment may seem time-consuming.
Spray the entire plant, including the top and bottom of the leaves and the stems.
Consider using a dormant spray over winter to smother overwintering spores.
Sulfur is mildly toxic to humans and other animals.
When you spray it, wear protective clothing.
It can also corrode metal, so use a plastic sprayer.
In hot weather, it can burns a plant’s leaves.
Home Remedies for Black Spot on Roses
Organic remedies may work for some gardeners.
Experimenting is encouraged if you keep the habit of frequently spraying roses to prevent black spots.
Which Roses Are Most Resistant to Black Spot?
Whether you use a synthetic and an organic fungicide is a question of personal preference.
Ensure there is good air circulation between plants.
Rose Black Spot.Penn State Extension.
Black Spot Of Roses - How Do You Treat Black Spot On Roses.
Texas A&M Agrilife Extension Service.
Black Spot of Rose.
What Should Neem Be Used For On Plants?.University of New Hampshire Cooperative Extension.
Powdery Mildew of Roses: Symptoms, Causes and Environmental Factors.Texas A&M AgriLife Extension Service.
Safe Rose Spray Recipe That Really Works.
The Myth of Milk and Roses.Washington State University.
Michigan State University Extension.
