The causative agent: Phragmidium (Phragmidium disciflorum, P. tuberculatum, P. rosae-pimpinellifoliae).
Harmfulness: in the cells of the infected plant, the processes of photosynthesis and metabolism deteriorate, the water balance is disturbed, as a result of which cracking of the cortex occurs, the stalks hit and thicken, the leaves, yellowish, fall off, the flowering stops. If you do not take measures to eliminate the disease, individual branches or the whole plant may die. Rusty rhizomes spread fairly quickly among healthy plants.
Rose rust is one of the most common diseases of this type of flower. Weak plants are the most susceptible to be infected. The causative agent strikes all the above-ground part of the bush: shoots, flower buds, petioles, in which the inside of the cavity begins to develop mycelium. The ideal conditions for inflammation of rust is the high level of humidity and the lack of light, which is especially true for greenhouses. In the open ground, the disease is most actively developed in the early spring, with the dissection of the first kidneys. In hot and dry weather, the development of a fungus is stopped. At the same time, it is easy to reveal rust in the early stages, because its symptoms are incomparable with any other disease.
A characteristic sign of the onset of the disease is the appearance on the stems and leaves of orange-red overshoes of round shape, similar to the pads. They contain spores of the fungus, which after ripening by airflows are transferred to other plants.
During the development of the disease, rusty spots cover the leaves of infected plants completely. At the final stage, the spots blacken, the leaves begin to dry up and crumble. There are noticeable cracks on the shoots. When cultivated in open ground, most of these stalks die in winter. Thus, with insufficient care, the fungus can survive on the shrub for several years, expanding along the inner cavity of the stems. When the exchange processes of the shrubbery due to the mushroom will not be possible - the plant dies.
The pathogen of disease hibernates well on plant residues in the soil, as well as on the stalks of rose bushes. Among the sources of this disease are honeysuckle bushes, which are most susceptible to it and become the distributor of spores to healthy plants. Also, you should know that on a damp and heavy soil, rust occurs in order more often. Qualitative prevention of this disease can completely eradicate it from your greenhouses or garden. To prevent rust, it is necessary to regularly and carefully examine the bushes for the presence of red spots - the first symptoms of the disease. All affected parts of the plant need to be immediately removed and burned. The same applies to fallen leaves. It is also important to ensure that the bushes are not too close to each other and there is sufficient air circulation between them, which helps to normalize the moisture level.