Black Spots on Roses

Have you ever seen a few black spots on your roses and been left puzzled as to what exactly caused them? ‘Black spot’ is the name given to the airborne fungus that is usually found in conditions that are warm or humid. Aside from temperature and climate being responsible for this fungus breeding, black spots can also be caused by overcrowding a rose.

Caring for roses

Roses can be the mainstay of any garden and with proper care, you can ensure your roses bloom to their full potential. From pruning your roses correctly to feeding them the appropriate nutrients, giving them room to grow and keeping their soil watered, you will be giving your roses the best possible chance to stay healthy.

Rose diseases

There are a variety of diseases that can not only destroy the look of your roses but also harm them. These can include black spots on rose leaves, powdery mildew, orange and brown discolorations caused by rust, and pests which can eat away at your roses.

Image: Rose rust.

While these rose diseases can be a big problem for your roses, they can be managed with proper care. Find out the type of disease that is affecting your roses so you can learn what steps you should be taking to stop the disease in its steps before giving it the chance to spread to the rest of your rose bush.

Black spots

Black spots are the most common type of rose disease. It is caused by Diplocarpon rosae, a fungus which can lead to black spots developing on the leaves and stems of rose plants. Before a black spot actually becomes a ‘black spot’, roses will start to develop a yellowing in some leaves.

If this yellowing goes ignored then black spots will form and spread quickly throughout the rest of the rose bush, eventually causing the plant to prematurely defoliate. While this disease does not kill the plant, the loss of leaves overtime can cause the plant to weaken and then become affected by other diseases or winter damage.

Causes of black spots

Black spots are caused by fungal pathogens that specifically attack rose plants. While the disease can infect stems, foliage tends to primarily be the target. This fungus favours conditions that are wet and humid, and spores are easily spread by water splash or rain.

If rose leaves are wet for periods longer than six to seven hours, then the risk of black spots developing greatly increases. Roses that are crowded are particularly susceptible to black spots as it is harder for air to circulate through the plant.

Treatment of black spots

If black spots have started forming on your rose bush, removing infected leaves will help to stop the disease in its steps and prevent more of the plant becoming infected. Learning the correct way to prune your roses will help to open up your roses to allow for more airflow and to remove diseased foliage.

If the disease has spread to more of your roses and appears to be reoccurring then do consider treating your roses with a suitable topical spray each week.

Prevention of black spots

The first step to treating black spots is taking appropriate steps for prevention. Allowing enough space for your roses to grow freely without crowding when you first plant them will make it easier for your foliage to dry off when wet.

When you do water your roses, make sure to only water the soil and not the foliage. This step will ensure that your roses are still getting the water they need to stay hydrated without creating a breeding ground for black spots to form. Adding mulch to the soil around the rose bush will also help prevent water from splashing up.

Whether you’re looking to plant a new rose garden or are looking for the appropriate tools to keep your roses thriving and healthy, Garden Express has all your rose-growing essentials to help you beat the battle of the black spot.