Morphological characterization of Verticillium dahliae isolated from olive trees in District Mardan

Verticillium dahliae is a soil-borne fungus that causes Verticillium wilt, a destructive disease of Olive trees worldwide. The common symptoms of Verticillium wilt in Olive trees include wilting, leaf rolling, chlorosis, defoliation, and dead brown leaves on sunny days. During the year 2020-21, one field of Olive Arched (17-acre area) was investigated for the incidence of Verticillium wilt located in Mardan District of Khyber Pakhtunkhwa. Root, stem and leaves, samples were collected from suspected plants, and cultured on potato dextrose agar (PDA) media for the isolation of Verticillium dahliae. Spores of the isolated fungal colonies were counted using a hemocytometer. The diameter of colonies was measured on PDA and complete media (CM) using a ruler with intervals of three days. Verticillium dahliae was isolated only from the olive tree roots, while no isolation of Verticillium dahliae was observed in stem and leaves samples. The average colony diameter after seven days on PDA and CM media was 4.6 cm and 2.4 cm respectively. Spores count for the pure colony was 3.44 x 107/ml conidia. It was concluded that the wilting observed in Olive trees was due to Verticillium dahliae in district Mardan.