Fungal pathogens of oregano occurring at the breeding plots in Ankara

Abstract

Fungal pathogens cause significant losses both in terms of quality and quantity on oregano (Origanum spp.) cultivation. Various fungal diseases on oregano grown in experimental plots of Ankara Field Crops Research Institute were observed in the years 2018–2020. A lot of symptoms; including dark brown necrosis, brown discoloration in the xylem vessels, brown spots and necrosis on the stems, splitting on the stem and branches together with brown, leaf spots and blights at varying sizes were observed. In addition, brown rust symptoms were also found. The fungal pathogens were isolated by plating disease samples taken from the peripheries of the necrosis or spots on culture media of water agar, potato dextrose agar and malt extract agar. The obtained fungi were identified by their morphological characteristics first, at least at genus rank and then by generating ITS1 and ITS4 gene sequences and comparing the sequences by the ones deposited in GeneBank. The most common and widespread pathogen was Boeremia exgua var. exigua and it was isolated from disease symptoms on branches, stems, collars and leaves from all the Oregano genotypes. From the brown necrotic areas at the collar, mostly Fusarium equiseti was isolated. From the leaf spots, along with Boeremia exgua var. exigua, Alternaria alternata complex and A. tenuissima were also recovered. The rust pathogen Puccinia menthae was determined on only Origanum vulgare var. gracile. Alternaria alternata complex, A. tenuissima, Fusarium equiseti, Boeremia exgua var. exigua were first records on Origanum spp. and Puccinia menthae on Origanum vulgare var. gracile in Turkey.