Fusarium species associated with apple trees decline in Isfahan, Iran

Apple (Malus domestica) is considered one of the most important economic products in Iran. Its cultivation is common in various regions and so far, more than 200 different domestic and foreign apple cultivars are identified, which Golden and Red Delicious cultivars are the most important cultivars in terms of cultivated area. Various fungal, bacterial, nematode, and viral agents cause weakness and decline of the apple tree and the quantitative and qualitative reduction of the crop. Apple root and crown rot is one of the important diseases of apple root, due to soil-born fungal pathogens, which lead to the decline of apple trees. The disease has a global spread and can occur at all ages of apple production. Different fungal species have been identified in infected regions so far, and it may be due to climate change. Sampling was performed from June to August 2019 from apple orchards with decline symptoms in Semirom and Padena in Isfahan province, Iran. Fungal species, including Fusarium solani, F. oxysporum, F. equiseti, F. acuminatum, and F. redolens, were morphologically identified. To confirm morphological identification, EF1/EF2 and ITS1/ITS4 primers were used in the PCR reaction. In vitro and greenhouse tests confirmed the pathogenicity of the identified species. As a result, it was proved that F. solani, F. oxysporum, F. equiseti, F. acuminatum, and F. redolens could be the causal agents of apple trees decline in Isfahan province, Iran, that F. solani, and F. oxysporum were more abundant.