Roses are covered with various spots due to various infections, pests, stress or inappropriate care conditions.
Brown spots with a black border indicate damage to the rose by brown spotting. The disease appears as a result of high temperature and humidity.
This type of spots can also signal other diseases. It can be septoriosis, pestalotia or phyllostictosis. Outwardly, the diseases are very similar, so you need to buy fungicides to fight them.
Cool and rainy weather provokes the formation of dark spots, which gradually merge and turn black. Over time, swollen, round and elongated areas appear on the affected leaves of the plant.
The disease is called black spot and its causative agent is the fungus Marssonina rosae. As a result of the disease, the diseased leaves fall off completely, immunity decreases and the rose does not bloom.
White spots on rose leaves are powdery mildew. It affects the whole plant without exception, even the fruits.
At first, a white coating appears on the affected parts of the plant. Then, over time, it turns brown-gray, the leaves curl, the rose weakens and risks dying in the winter. The causes of the disease are excessive air humidity, excess nitrogen in the soil, calcium deficiency and too dense planting of plants.
Yellow spots on the plant appear due to a deficiency of iron and potassium in the soil. Over time, the plant acquires a reddish-purple color. To cure roses, they need to be fed with potassium-based fertilizer.
During excessive exposure to direct sunlight, rose leaves acquire a bright purple and cherry color. Such exposure to the bright sun causes sunburn on the plant. Roses must be shaded or transplanted immediately to protect the plants.
The appearance of rufous spots on the leaves of the plant signals the impression of rust. First, yellow-orange bumps appear on the reverse side of the leaves, and later the infected leaves turn yellow and fall off. The reason for the development of the disease is high air humidity.
What to do in case of severe damage
All diseased parts of the rose should be cut off and burned. Healthy shoots must be cut at the level of 2-3 buds from the base. Treat the affected bushes with a plant treatment recommended by a trusted store.
In case of severe damage, the plants cannot be treated. They should be dug up and burned before the infection spreads to healthy plants.