Roses are the crown jewels of any garden, but they can be vulnerable to pests and diseases, particularly black spot. Black spot disease causes blemishes on leaves that result from a bacterial or fungal infection that can grow on any type of plant, though it particularly affects fleshy-leaved plants, like roses. Although it is not always a fatal affliction, it can easily weaken the plant and affect the quality of its blooms as well as open the doors to other infections.
While synthetic chemicals might offer a quick fix, many gardeners prefer natural solutions that keep their roses healthy without harming the environment. Despite it not being a cure, experts at Gardening Know How recommended using neem oil as a way to prevent black spot from forming and damaging your roses.
They said: “Neem oil is a natural product that has fungicidal properties. It is not a cure for established black spot infections, but it is a practical and effective management strategy.
“When used regularly, it helps to prevent the germination of fungal spores.” The experts also pointed out that neem oil is “effective” at treating powdery mildew on roses.
This is a commercial oil that is derived from evergreen neem trees, and it works great as a natural fungicide, preventing the black spot-causing fungus from thriving.
Scan the pesticide aisle of your local garden centre and you’ll likely see several products containing neem oil. Unlike synthetic chemicals, they’ll usually be labelled safe for organic gardening.
To prevent black spot on roses, spray neem oil on roses every seven days specifically to the leaves.
For this solution, dilute one to two tablespoons of neem oil in 3.5 litres of water, and add one to two teaspoons of washing-up liquid.
If black spot disease is already infecting your roses, remove all the diseased leaves as soon as possible, as the fungus can spread quickly.
Burn or dispose of the leaves in a bin bag. Do not add it to your compost, as the disease can transfer back to your rose bushes.