First Report of Cabbage Yellows Caused by Fusarium oxysporum in Egypt

In February 2017, Cabbage plants cultivar Balady showing slow wilt, were observed in Faquose county, Sharkia governorate, Egypt. Symptoms started on the lower leaves and moved upwards; leaves of young plants were twisted and became yellow on one side, and eventually, the affected leaves turned brown (Fig. 1) and when the stem was longitudinally cut, a brown colour was seen in the vascular system; (Fig 2). Fusarium oxysporum was consistently isolated from lower stem portions on potato dextrose agar (PDA) incubated at 25°C for 7 days. Identification of isolated fungus was preformed based on its morphological characteristics. Microscopic observations of Fusarium oxysporum revealed that the mycelia of the isolates were delicate, white to pink or purple tinge, sparse to abundant than floccose, margins slightly lobed or smooth on PDA. Microconidia formed singly, oval to reniform and without any septation. Conidiogenous cells bearing micro- and macroconidia are monophialides type. The size of microconidia ranged from 7.50 - 10.25 and 2.50 - 3.50 μm. Macroconidia were falcate to almost straight, the size of the macroconidia ranged from 20.27 - 30.50 and 5.00 - 6.75 μm (Fig. 3). Reproduction of symptoms on inoculated healthy Cabbage plants and the re-isolation of Fusarium oxysporum from the inoculated plants but not from plants inoculated with water fulfilled Koch’s postulates and confirmed its pathogenicity. According to the available literature and the best of our knowledge, this is the first report of cabbage yellows caused by Fusarium oxysporum in Egypt.