Hello! Considering the period we are in, at the moment, it is recommended to remove and destroy the affected portions and to apply a fertilizer with a high potassium content, such as (by spreading it around the roses, in a dose of 30-50 g/sqm, followed by incorporation and watering).
This fertilizer increases frost resistance and improves the water balance of plants. Subsequently, after leaf fall, it is recommended to carry out specific treatments during the dormancy period with copper fungicides such as: , or and horticultural oil (10-14 days after the fungicide application): , or . More information about treatments during dormancy can be found in the following article: Winter treatments with oils and copper-based products . From spring onwards, it is advisable to regularly apply a fertilizer that is specially formulated for the requirements of this species, with a regenerating and hardening effect on roses, such as or , applied according to the instructions in the product description. In spring, in case symptoms of a disease appear, such as: Rose black spot (Diplocarpon rosae) - identify and control .
More tips and information for rose care can be found in our articles: Roses, planting guide and care work ; Roses, pest and disease control ; Protecting roses from frost ; Rose pruning - specific guide .