Impact of some technological methods of growing sage on the spread and development of peronosporosis

Abstract

Common sage (Salvia officinalis L.) is a valuable essential oil-bearing and medicinal crop whose cultivation has significant economic and pharmacological importance. However, one of the major constraints in its production remains downy mildew, a dangerous fungal disease caused by Peronospora lamii A. Braun. The outbreak and progression of the disease are directly dependent on meteorological conditions and agronomic practices applied in cultivation technologies. The pathogen develops actively under cool and humid conditions, infecting the aboveground plant organs, which leads to a reduction in yield and deterioration in the quality of the raw material, Folia Salviae. The paper presents the results of long-term studies conducted at the experimental fields of the Research Station of Medicinal Plants of the Institute of Agroecology and Environmental Management of NAAS, aimed at determining the effects of plant nutrition area (row spacing) and nitrogen fertilizer rates on the development and spread of downy mildew in common sage. The studies demonstrated that row spacing is a key factor in shaping the phytosanitary status of sage plantations. An optimal inter-row distance of 70 cm improves crop aeration, reduces the duration of leaf surface wetness, and consequently decreases disease development by 13–27% compared with the conventional row spacing of 45 cm. Under this plant density, disease incidence did not exceed 47.4%, whereas in dense stands it exceeded 60%. It was demonstrated that the application of high nitrogen fertilizer rates exceeding 60 kg/ha (N60) stimulates vegetative growth but simultaneously creates favorable conditions for pathogen development, particularly under excessive plant density. This may result in a sharp increase in the risk of epiphytotics and a significant deterioration in the quality of medicinal raw material. Based on the obtained data, a cultivation technology for common sage is recommended that involves a row spacing of 70 cm combined with low nitrogen fertilizer rates (N30). This approach effectively restrains the development of downy mildew, reducing disease incidence to 6.4–7.9%, which is a prerequisite for the stable production of highquality medicinal plant raw material. The research results have practical significance for the environmentally sustainable cultivation of common sage under conditions of climate change. They demonstrate that regulating crop density and applying rational fertilization practices enhance the phytosanitary resilience of agrocenoses, maintain yield levels, and ensure the stable production of high-quality medicinal plant raw material.