Pathogen: Sphaerotheca pannosa refers to Erysiphales.
Infection is rapidly spreading, affecting mainly young plants, which, as the disease progresses, begin to rumble, leaves fall and eventually die. The mushroom-causative agent has a high degree of mutation and it is widespread.
Powdery mildew of roses is one of the most common diseases of pink bushes. Most often it damages the growing in greenhouses and indoor roses. Erysiphales develops rapidly, infecting new plants. Favorable conditions for development are hot and humid weather during the day, with lowered temperatures at night and the release of condensation on leaves. In cool weather, the fungus is not generally distributed. It also enhances the development of illness with a lack of light.
On the outside of the leaf whitish plague (or with a light pink, gray or brown shade) appears. At first, these are small spots that can be easily wiped out by hand. But already within 1-2 days they grow, cover the leaves completely and pass on their inner side.
The mycelium of the fungus rapidly grows, to the touch and outwardly it can be compared to a felt cloth. Further on it formed fruit bodies, which after ripening, begins sporulation and infestation of other plants. The whole process can take 1-2 days under favorable conditions. Mycelium fungus parasitizes on leaves and prevents photosynthesis, the infected plant does not absorb nutrients, begins to dry. As a result, a sick rose bush without treatment dies for 5-7 days. This is especially true for young shoots and plants that do not yet have an odorless part.
The spores of powdery mildew fungus are easily spread between plants with the help of air streams, and even wind blasts are not required for this. Also spores are well transmitted with splashes of water and transported by insect pests (thrips, aphids, scales). The causative agent of the disease also hibernates in soil on plant remains.
Taking into account such prevalence and activity of powdery mildew, preventive measures to control it should be obligatory for all those who grow roses. Prevention includes items: