Roses are a beautiful addition to any garden, but gardeners need to keep an eye out for black spot disease, which can devastate these flowers if not caught early.
Black spot leaf disease is common a fungal infection which looks like dark spots or blotches on the leaves of roses and tends to be more common from late spring to early autumn when roses are blooming.
While this disease will not outright kill roses, it will cause the plant’s leaves to shed, turn yellow, stop flowering and greatly weaken the plant, leaving it vulnerable to other diseases and pests which can eventually harm it.
If black spot disease makes its way into garden soil it is very difficult to get rid of, but David Domoney, a horticulturist and celebrity gardener known from Love Your Garden has shared that is easy to prevent or manage the disease once you know what to look out for.
He said: “There is no cure for black spots on roses. However, there are several things you can do to minimise the effects and avoid plants succumbing to it in the first place.”
How to control and prevent black spot disease
Black spot disease needs moisture and heat to germinate so it is more likely to spread on humid or rainy days during warm temperatures.
The best way to prevent the disease is to make sure rose plants have enough airflow and are watered at the right time of day to prevent them from becoming waterlogged.
David said: “Avoid overcrowding around rose plants to allow air to circulate around them. Try to water in the morning so leaves will hopefully dry out quicker than if watered in the afternoon or early evening.”
Make sure to always water roses deeply at the base of the plant and try to avoid the leaves as it will reduce the spreading of disease.
Pruning roses in late winter or early spring is often needed at least once a year to help reduce the chances of fungal diseases, but it is not recommended to prune in the summer as it can stress out the plant during the hot weather and make it more susceptible to disease.
Instead, you can deadhead roses at this time of year to remove any dead or diseased foliage which may be harming the plant but only do so if you are sure it is diseased.
David said: “Pick off infected leaves when first seen in the spring to help minimise its spread. Do this only if you’ve had a definite diagnosis that the blotches are black spot. This is because removing leaves can limit the plant’s ability to grow well.”
Preventing black spot disease can be tricky but early detection is the key is managing this disease, so make sure to check your roses regularly.
Some people treat rose disease with a baking soda solution to deal with it naturally, but if you suspect your roses may have black spot disease it is best to visit your local garden centre for advice or a fungicide.
David said: “There are also proprietary chemical sprays available at most garden centres including sulphur-based products. It’s crucial to start spraying early in the season and apply every four to six weeks.
He added: “With this guide on black spot on roses, you’re one step closer to having thriving beautiful roses clear of disease. If you need specialist advice, you can get in touch with your local garden centre who will be more than happy to give you any tips and advice.”
