The most serious disease in roses is the black spot. It is caused by a fungus that infects the leaves and significantly decreases the vigour of the plant. As long as the leaves remain on the plant, expect to see leaf marks from spring that will linger.
The fungus is very diverse genetically and new strains emerge rapidly. Unfortunately, this means that because new strains of the fungus emerge. This is why it is important to use Black Spot On Roses Remedy such as https://greenacresdirect.co.uk/Sulphur-Rose.html to help combat the issue as soon as it begins to develop.
In the black spot lesions on the upper leaf surface, the fungus develops spores and these disperse into water to initiate new infections. For the illness to build up, wet conditions are needed, but most summers in the UK are plenty wet. The fungus spends the winter on fallen leaves and also on young stems and buds with dormant infections, developing spores to infect young leaves in the spring. It is important to remove any leaves that have fallen on the ground around the roses as soon as possible to help control the spread of the fungus.
Nearly all their leaves can be shed by badly infected plants and their growth and overall plant health is greatly diminished. This can be displayed by a plant that is not growing as well or as quickly in size as you might have initially thought. The disease has been blamed in recent decades for a drop in the popularity of roses in UK gardens as more and more gardeners search for ways in which to combat this disease.