Skip to main content

Black spots on your roses: fungus, or something else?

Your beautiful rose bushes are a conversation starter, an attractive focal point in your garden, and simply your pride and joy when it comes to your gardening adventures. It’s certainly a big disappointment when they suffer damage, become stunted, or start to show signs of disease. One of the most common and devastating plagues for rose bushes is the appearance of black spots on the leaves. To keep your blooms healthy, stick with us to learn more about what causes black spots on roses, how to address them, and how to prevent them from returning to your prized rose bushes in the future.

rose bushes against wooden gate
Image used with permission by copyright holder

What causes black spots and is it harmful?

When you see black spots on your roses, the culprit is almost certainly a fungus called “Diplocarpon rosae,” which thrives on plants that hold a lot of moisture. These fungal spores germinate on a wet surface and eventually cause the affected leaf to become yellow, wilt, and fall off. The spores then spread to other parts of the plant through the air and via water droplets. As more leaves die and fall off of the plant, it will become weak, produce fewer buds, and may eventually die if the fungal infection remains untreated. When you see the first signs of black spots on your rose bushes, take action immediately to reduce the spread of these spores.

Recommended Videos

How to treat black spots on roses

Remove infected foliage with caution

Black spot spores are resilient and they spread easily. Since you can’t save infected petals, it’s crucial to remove fungus-laden leaves and branches when the plant is dry. This prevents the spores from spreading through water droplets as you work. Once you’ve pruned away the black-spotted areas, don’t compost the removed pieces. The spores can remain compost bin and re-infect plants once the compost is laid.

At the end of the season, remove all leaves and other debris since spores may even survive the harsh winter and infect the plant once more when it blooms again.

Should you treat roses with fungicide?

Fungicides effectively stop the spread of this fungus in its tracks. In most cases, a 7-14 day treatment is all it takes to prevent the infection from spreading. If you’d rather treat your blossoms naturally, there are some other non-chemical options for your organic yard.

Natural and home remedies

Neem oil

Neem oil is a natural fungicide that plants soak up into their system, preventing the need for repeated application. Simply mix two tablespoons of mild soap into a gallon of water, then add two tablespoons of neem oil. Spray the solution directly on the whole plant, treating all leaves and stems.

Baking soda

Baking soda is an antifungal that’s safe for humans and pets, so you can prevent the spread of black spots without any harmful chemicals. Mix one teaspoon of baking soda and one teaspoon of mild soap into one quart of water. Spray directly on the entire plant.

red rose fully bloomed
Image used with permission by copyright holder

Prevention is key

Since these spores thrive in moist conditions, prevent fungal growth on your rose bushes by reducing excess moisture.

  • Space your bushes properly. This allows good airflow between your plants that will dry pools of water.
  • Water appropriately. Avoid watering the plant’s leaves and only water the soil beneath them.
  • Lay mulch. This covers the soil and absorbs water better so it doesn’t splash back onto the petals when watered.
  • Prune often. Pruning infected leaves as well as excess foliage will increase airflow and prevent moisture from building up.
  • Maximize sun exposure. Plant your roses in an area where they’ll get a lot of rays so the sun can dry the leaves quickly.
  • Choose a resistant plant variety. Many rose bush varieties, like the fire-engine-red Altissimo, are resistant to fungal infections.

Rose bushes are the star of any garden. When you’ve worked hard to plant and care for your rose bushes, it’s devastating when they show signs of a damaging infection. While you can’t get rid of the spots on the affected leaves, you can take some precautions to stop the spread of the infection and prevent it from devouring the entire bush. With some organic or chemical fungicides as well as careful pruning and maintenance, your rose bushes will remain healthy, flourishing, and black spot-free.

Editors' Recommendations

Veronica Sparks
Veronica Sparks is a writer from Milwaukee, Wisconsin who loves writing about gardening, home décor, and DIY life. She’s…
6 kinds of perennials that bloom in the summer for a gorgeous garden all season
Hostas, lily of the valley, and more: These perennial blooms will brighten your outdoor space
Chair beside blooming flower garden

Gardening is a lot of work, but it can be well worth it if you do a little homework before you start digging. If you want your flower beds and garden to bloom for longer than a few weeks, you can't just plant seeds without care and expect long results. In fact, many perennial plants have relatively short flowering seasons, leaving your garden looking a little bare for a good portion of the summer. And after all that work, there is nothing worse than looking at a bare garden. So, how do you get your garden to look gorgeous all summer? Plant perennials that bloom all summer long.

We’ve pulled together a list of perennials that will boast beautiful blossoms throughout the entire summer and return year after year with an abundance of color and fragrance. For a more interesting-looking flower bed, be sure to incorporate a variety of heights, a cohesive color scheme, and flowering plants that thrive in varying amounts of sunlight. Check out the recommendations below to build long-lasting floral arrangements you can enjoy for months on end.
What are perennials?

Read more
Avoid a huge fire risk in your home: How to clean your dryer vent
Use these tips and tricks for a safer, more effective dryer
Outside dryer vent

A clean home can cultivate peace and kick stress to the curb, but it can be difficult to keep up with those often-neglected areas of the home. The laundry room is one of those areas, but it's also a space that's downright dangerous to neglect. In fact, FEMA reported that clothes dryers cause around 2,900 fires in residential buildings every year, resulting in widespread damage, serious injury, and even death.

However, you can prevent catastrophe in your home by cleaning your dryer regularly. If you don't know where to start, don't worry. We’ll walk you through how to clean the dryer vent so your laundry room and your home will be both clean and safe.
What you need
Before you begin, gather these items:

Read more
This is how much it really costs to replace the windows in your home
From window type to material, the scope of your project will affect your window replacement costs
Man installing bottom of window trim

Replacing a window is a bigger project than many homeowners realize. With so many options to choose from, windows come in a variety of materials and styles, each affecting their overall cost. Today, we’re discussing the window replacement cost, so you can get an idea of what to expect for your next renovation.

How much does it cost to replace a single window on average?
The cost to replace a window can range from anywhere between $450 and $1500, with the average price of a window replacement costing $730, according to MarketWatch. Depending on the type of window, the material, and the location you live, window replacement prices can change based on the scope of your project.

Read more