Black spot on roses: how to treat to overcome the scourge

Marssonina rosae

, which begins to develop with the arrival of spring.

First of all, the decorative quality of plants decreases, but this is only the visible part of the problem. With severe infection, not only the leaves, but also the young shoots suffer. The bush loses its leaf mass and constantly forms new shoots that do not have time to ripen before the cold weather. This leads to reduced resistance, and without treatment the plant may die within a few years.

Selection of fungicides for disease treatment

Black spot treatment is carried out using antifungal drugs (fungicides). There are many effective means to combat the disease, which belong to three main groups of fungicides:

copper-containing (Bordeaux mixture, Abiga-Peak);

systemic (“Skor”, “Topsin-M”, “Topaz”, “Fundazol”, “Raek”);

system-contact (“Ridomil Gold”, “Quadris”, “Ordan”).

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However, when treating an affected plant, it will not be possible to limit yourself to one drug, since each group of drugs has negative aspects and limitations. For example, copper-containing drugs can accumulate in the soil.Some systemic fungicides, such as Fundazol, are toxic and are not recommended for annual use; others have restrictions on the number of applications per season. Less toxic substances may become addictive.

Therefore, the treatment of black spot requires an integrated approach. To prevent the pathogen from becoming addictive, it is necessary to alternate drugs with different active ingredients, as well as alternately use contact, systemic and copper-containing fungicides. It is also necessary to monitor the effect that the drug has in order to assess the advisability of its use.