This is one of the garden diseases specific to all types of roses. It takes the form of a black spot fungus and produces spores, which are released under wet conditions. Rose black spot thrives in warm, wet weather, especially in the spring.

Leaves less than two weeks old are most susceptible and spores can survive on fallen leaves and within the soil.

It can be passed from plant to plant as well as on hands, clothing or tools.

How to spot rose black spot

It is important to remain on the look out for various garden diseases and rose black spot is no exception.

Look out for the first signs of small pin-head sized black spots on the leaves, if unnoticed the spots increase in size to become large black or dark purple spots on the surface of the leaves or stem. The problem can get worse – the foliage eventually turns yellow and drops prematurely.

These symptoms can become visible within 72 hours after infection during warm, wet weather. A secondary infection cycle can develop within 10 days.

How to treat rose black spot

If you discover a black spot on roses then the first thing to do is prune off the damaged part of the plant. Rake around the plant and burn any infected foliage. Don’t put the diseased plants on the compost, as the fungus will be recycled back into the garden.

Once you’ve removed the diseased parts from your rose bushes, you can use a fungicidal soap or sulphur to minimize the likelihood of further attack.

There are some popular home remedies if you prefer the organic approach.

For example, dissolve 1 teaspoon baking soda in 250ml of water; add a few drops of liquid soap to the mix to help it cling better to the foliage and spray infected plants with rose black spot thoroughly.