Distribution and Biology of Black Rot and Its Effect on Yield of Cabbage in Harer Zuria Province
1993
Teman Husien | Tarekegn Geleta (department of Plant Science, Alemaya University of Agriculture, Dire Dawa (Ethiopia))
Survey of black rot of cabbage was carried out in Harar Zuria province and the disease was found widely distributed with incidence varying from 5 percent to 50 percent. This was confirmed with the presence of the causal agent of this disease in all infected cabbage plants collected from different localities of the province. Different inoculation methods were compared under greenhouse conditions. The most effective method was the leaf-tip clipping procedure where the tips of young leaves were clipped with sterile pair of scissors and dipped in acqueous bacterial suspension. The effect of black rot on yield of cabbage was investigated under artifical disease pressure. Disease severity of 14 percent resulted from inoculation cabbage plants 3 times at 20 days intervals reduced yield by 35 percent (11 t/ha). The importance of infected seeds and/or infested soil on the intensity of black rot of cabbage was studied and plants grown from infected seeds on infested soil showed the highest percentage of infection. Both infected seeds and infested soil were known to be major source of inoculum for black rot indicating that the disease is seed as well as soil borne.
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