Apple tree Alternaria (malus domestica Borkh.) and ways to reduce its harmfulness in the non-chernozem zone of Russia

Abstract

The research was conducted on the territory of the educational and experimental farm of the K.A. Timiryazev Russian State Agrarian University of Agriculture in Moscow in 2020-2023. The examination of apple-tree plantings, ornamental plantings, and weed vegetation was carried out for three years with determination of pathogens of the main diseases by microscopy method. The Alternaria fungi species membership were identified by morphological features of conidia and sporulation habitus, and the specific pathogen species was confirmed by PCR analysis. Two unspecified species of Alternaria tenuissima and Alternaria infectoria fungi were found to infect apple trees and other species of the surveyed plants with Alternaria blight. The fungus species Alternaria tenuissima was predominantly recorded on apple trees. Out of 186 examined apple cultivars, the development of Alternaria blight was found in 85.5% of the cultivars with different ripening periods. The apple cultivars most resistant to Alternaria blight were identified. The apple cultivars, in which the damage of fruits by Alternaria blight was recorded, were identified. Infestation of apple seeds by fungi of Alternaria genus obtained from fruits affected by this pathogen was determined. The possibility of high Alternaria blight infestation degree in apple tree seedlings was detected. A high degree of Alternaria tenuissima and Alternaria infectoria fungi development was recorded in a number of orchard-protecting and ornamental plants, as well as in weeds, and their possible role as reservoirs and transmitters of infection to fruit crops was established. The efficacy of fungicides: Luna Tranquiliti, KS; Skor, KE; Medea, ME; Zato, VDG; Horus, VDG; Coside Super, VDG in suppressing Alternaria blight development on apple cultivars of different ripening dates has been compared.