FEATURES OF THE MANIFESTATION OF CALENDULA OFFICINALIS POWDERY MILDEW

Calendula officinalis are an annual light-loving, moisture-loving herbaceous plant, the inflorescences of which are raw materials for the pharmaceutical, food, and perfumery and cosmetic industries. The species composition of pathogens, their features of manifestation and development on medicinal plants are insufficiently studied. Powdery mildew is one of the most common and dangerous diseases of medicinal plants. The appearance of powdery mildew usually coincides with the flowering phase of medicinal plants (the month of June). With strong development, the causative agent of the disease leads to the drying of leaves and stems and the death of plants. Diseased plants lag behind in growth, generative organs recover later after three collections of raw materials. During the research period (2019-2021), the prevalence and development of powdery mildew of medicinal plants was monitored, its harmfulness and development features were determined, and the resistance of various varieties was assessed. When accounting for powdery mildew, the following indicators were evaluated: the number of affected plants - in percent; degree of damage - in points visually. Generally accepted methods in medicinal plant breeding were used for the research. The total size of the plots is 20-25 m2, accounting 20-30 m2, with four repetitions. The field evaluation of the resistance of varieties of medicinal plants for resistance to diseases was carried out on a natural infectious background during the period of maximum development of diseases (2-3 times during the entire vegetation period - June-August). High resistance to the powdery mildew pathogen during the research period was observed in the varieties Tangerine Twist, Dejavu, Indian Prince, Orange King, Silk Kiss, Dejavu, Indian Prince, Red Doctor Citrongelb, Red Buff and Sherbet. Cremebrule, Citron, Fiesta and Princess varieties had a weak susceptibility to the pathogen of powdery mildew. Varieties Monarch, Pink Surprise, Orange Heart, Magic Heart and Touch of Red were susceptible to powdery mildew.