Abstract. The aim of the study was to determine the fungi occurring on fallen leaves of the rhododendron Rhododendron L. The observations were carried out on eight taxons of rhododendrons. The fallen leaves were plated on PDA medium. 18 species of fungi were isolated. Among them dominant were: Alternaria alternata, Pestalotia sydowiana, Penicillium verrucosum v. cyclopium, Mortierella alpina, Cylindrocladium scoparium, Cylindrocarpon destructans, Sordaria fimicola and Humicola fuscoatra v. fuscoatra.

Fungi occurring on the fallen leaves of rhododendron

Summary

The aim of the study was to determine the fungi occurring on the fallen leaves of the rhododendron. Observations were carried out on eight taxons of rhododendrons. Infection index of rhododendron leaves was assessed and the occurring fungi were isolated. The most frequently occurring fungi were: Alternaria alternata, Pestalotia sydowiana, Penicillium verrucosum v. cyclopium, Mortierella alpina, Cylindrocladium scoparium, Cylindrocarpon destructans, Sordaria fimicola and Humicola fuscoatra v. fuscoatra. Less frequent were: Epicoccum purpurascens, Phoma chrysanthemicola, Phialophora richardsiae, Arthrobotrys arthrobotryoides also Botrytis cinerea. It was found out that Alternaria alternata played a dominant part in the process of falling of rhododendron leaves. Good health properties characterized the cultivars of R. brachycarpum ssp. tigerstedtii, with the exception of ‘Mikkeli’, which manifested in the low infection index. The worst health properties characterized the cultivar ‘Lachsgold’, steming from R. wardii, which may be the reason for excluding this cultivar from further breeding works. Low infection index in R. degronianum ssp. yakushimanum FCC confirms the usefulness of this garden form in breeding evergreen rhododendrons.