Hello. In the attached picture the presence of some scale insects can be seen, most probably the species Saissetia oleae (Scale insects in ornamental plants - pest management).
First of all, it is recommended to remove the severely affected leaves as well as the visible pests, as far as possible. Subsequently, for the control of scale insects at different stages of development, insecticide treatments with products such as and are recommended, alternately. More precisely, the first treatment is recommended to be carried out with , in a dose of 7.5 ml/10 L water, and after 7 days the treatment can be applied with , in a dose of 3 g/10 L water. To increase the effectiveness of the insecticides, it is recommended to add an adjuvant such as , in a dose of 2 ml/10 L to the solutions. Spray the mixtures as finely as possible, so as to achieve an even distribution on the plant, both on the underside and topside of the leaves and on the stem (). After they die, these pests can remain on the stem and leaves, so it is recommended to remove the remaining specimens with a damp sponge.
Then, 7-10 days after the end of the treatments, to support the regeneration of the plants after these stressful conditions, you can consider applying a fertilizer such as , as recommended in the product description. From spring onwards, and during the growing season, you can consider the regular application of a plant revitalizing fertilizer such as or , according to the instructions in the chosen product description.