The leaves of your favorite rose bushes have become covered with black spots. It is most likely a cryptogamic disease which affects the flowering of your shrubs. Don’t panic, our gardening team is here to help you understand and combat this problem. We will introduce you to the best home spray for black spot disease on the leaves of your rose bushes as well as other natural treatments.
Here is the best natural treatment for black spot disease
If you take care of your rose bushes properly, there are chances of avoiding diseases
Before you dive in, consider that the disease that causes black spot on rose bushes is almost impossible to eliminate 100%. However, with the right tips and products, you can limit its development.
The disease that causes black spot on rose bushes is almost impossible to eliminate 100%.
What is Marsonia?
Marsonia is a cryptogamic disease of roses, very easy to recognize. Indeed, it is a fungus that causes circular black spots on the leaves which spread up to the stem. Over time, the spots become more and more visible. Yellow halos appear around the black spots. The next stage is characterized by leaves that dry out, turn yellow and eventually fall off. It is a disease that is very widespread among rose bushes. It is not harmful to them, but it stops flowering and eventually you will end up with a bare plant. What’s more, marsonia eventually weakens rose bushes. It begins in June and can last throughout the summer.
It is a fungus that causes circular black spots on the leaves
This disease is easily recognizable
The fungus which is responsible for this disease multiplies thanks to spores which are dispersed by wind or water. Therefore, we can say that it is very contagious. It grows best when the days are warm and the nights are still cool. Preventive measures must be taken, starting in the fall. And we’ll see which ones right away.
Here is a photo of the beginning of the disease
Prevention is better than cure, our saying goes. Here are some treatments to plan for in spring to avoid the appearance of black spots which will spoil the visual appearance of your garden.
When it comes to black spot disease, prevention is better than cure
- Regularly collect leaves from the ground,
- In autumn, spray your shrub with Bordeaux mixture which is a fungicide that contains sulfate and copper.
- Take more resistant varieties.
- From the start of spring, spray your shrubs with a mixture of water and nettle or horsetail manure every two weeks.
- Water early in the morning so that your leaves have time to dry while avoiding getting them wet.
- Avoid planting rose bushes in humid and/or shady areas, as well as in heavy soils.
- Space the plants well to ensure good air circulation and prevent the appearance of this disease.
- Plant your rose bushes in a location where they receive morning sun so that the sun can dry the foliage. A location in full sun, all day, is also very favorable.
- Apply a layer of mulch around your rose bushes to prevent spores in the soil from spreading. While avoiding mulching with rotten wood.
- Some gardeners recommend spreading a little cornmeal around the base in spring. The latter contains a fungus that kills disease pathogens.
Make sure your garden is always tidy and clean
However, if the infection has already started, don’t panic, you can still cure them. Your first instinct would be to remove all contaminated leaves. Clean the soil around the bases of rose bushes to prevent spores from spreading and infecting new growth. And if you notice any stems that look diseased before new leaf growth, they should be removed immediately. Put the cut leaves in a bag and throw them directly into the trash. Because there is only a slight breeze left to bring the spores back to your rose bushes.
Cut off absolutely all contaminated leaves
100% organic homemade spray recipes
The second thing is to start spraying with a spray, preferably homemade. The first recipe calls for the use of baking soda. Mix a spoonful of baking soda with a liter of warm water with a spoonful of liquid soap.
Baking soda is widely used in gardening
Here is the most successful recipe. It is to be used every week
Mix in water:
- White vinegar – 1 tbsp
- Baking soda – ½ tbsp
- Dishwashing liquid – 1 tbsp
- Vegetable oil – 1 tbsp
Start spraying with prevention methods in May
From June to mid-September, you will have to apply one or more of these remedies to keep black spot disease at bay and protect your rose bushes.
From June to mid-September, apply a natural treatment for black spot disease
In humid weather, treat plants with a copper product once every three weeks. This can be Bordeaux mixture or oxychloride. Note that horsetail decoction is another excellent variation that is rich in silica.
In humid weather, treat plants with a copper product once every three weeks
Water-soluble sulfur is very useful in combating this disease. This may seem a little aggressive for your rose bushes, but in reality, it is super effective against fungi. However, it can be a little toxic for us and for animals. It is therefore imperative to protect yourself and use a plastic sprayer. Avoid spraying with sulfur in very hot weather, as it can burn your leaves.
Water-soluble sulfur is very useful in combating this disease
Some gardeners swear by milk. Indeed, it cannot prevent the spread 100%, but can reduce it considerably. These home remedies are worth trying, however no results are guaranteed.
It is not impossible to defeat marsonia
Provide mulch for your rose bushes if you have doubts
Natural Treatment for Black Spot Disease
Make your own homemade spray for black spot disease on the leaves of your rose bushes