Diseases of roses of the tea-hybrid garden group of the collection of the Stavropol Botanical Garden

Abstract

Relevance. Conducting research on the resistance of hybrid tea roses to phytopathogenic harmful organisms and determining the species composition of pathogens and factors affecting their developmen.Methods. The objects of the study were the causative agents of fungal diseases of varieties of hybrid tea roses from the collection of the Stavropol Botanical Garden. The research was carried out using the Methodology of state variety testing of agricultural crops.Results. The results of studying the species composition of mycosis pathogens on varieties of roses of the tea-hybrid garden group of the collection of the Stavropol Botanical Garden are presented. The nature and degree of damage to plants is described, the causes are established and methods of containment of diseases are developed. The most harmful and common diseases on hybrid tea roses in growing conditions are: powdery mildew (Podosphaera pannosa Lew. var. rosae Voron.); downy mildew (Peronoplasmopara sparsa (Berk.) Uljan.); rust (is caused by 2 pathogens — Phragmidium mucronatum (Pers.) Schltdl., Phragmidium tuberculatum Mϋll. Hal.); gray rot (Botrytis cinerea Pers.) and leaf spotting of different types: black spot (Diplocarpon rosae F.A. Wolf. = Marssonina rosae (Lib.) Diet.); septoria (Septoria rosae Desm.); cercosporiasis (Cercospora rosiola Pass.), the development of which was facilitated by meteorological conditions over the years of research. Evaluation of hybrid tea cultivaris of roses for resistance to fungal diseases was carried out in 2019-2021 in the collection of the Stavropol botanical garden on a natural infectious background on a 5-point scale during the period of mass spread of diseases. Despite the fact that all cultivaris of hybrid tea roses are affected by fungal diseases, it has been found that different cultivaris are affected differently. According to the degree of resistance to the complex of diseases, 4 cultivaris received 1 point (practically resistant), 52 cultivaris received 2 points (weakly affected), 74 cultivaris received 3 points (mediumly affected), 33 cultivaris received 4 points (strongly affected). Regular monitoring of the phytosanitary state of the studied cultivaris, biological and chemical protection measures made it possible to reduce the massive spread of fungal diseases and preserve the decorative effect of plants.