Tarla Divine Nfor , Fontem Dominic Ajong and Langsi Ivo Nuincho
Banana is one of most important food crops that are consumed worldwide. Seven high yielding and disease-free varieties (Jaffa, Adi, Williams, Gal, Nandi, Asdia and Ofir) were obtained from tissue culture in Du roi (South Africa) and Rahan (Israel) laboratories. The responses of these varieties to black sigatoka caused by Mycosphaerella fijiensis were evaluated in the nursery of C.D.C Ndongo Banana Plantation in Tiko, South West Region of Cameroon. A completely randomized design was used with 12 replicates. Data were collected on leaf emission rate (LER), number of days from unfurling of heart leaf to the formation of streaks (incubation period), number of days from streaks formation to spots formation (latency period), youngest leaf with infections (YLI), youngest leaf with spots (YLS) and percent disease severity at leaf number (LN) 2,3,4,5,6 and 7. The weekly leaf emission rate for banana varieties varied from 1.2 to 1.4 being higher for Adi and Ofir compared to Jaffa and Gal. Adi and Ofir had the longest incubation period of 28 and 25 days, respectively. A significant difference was obtained between varieties for latency period. Youngest leaf with infections (YLI) was obtained at LN 3 for susceptible varieties while Adi and Ofir with LN 4. Youngest leaf with spots (YLS) was obtained at LN 4 for susceptible varieties while for Adi and Ofir it was at LN 5. The highest percent disease severity (42%) was obtained for Gad and Jaffa at LN 7, while the lowest (10%) was obtained for Adi and Ofir at the same period. Two deleafing cycles and weekly incision of necrotic spots of the disease were performed on Jaffa, Gal, Williams, Nandi and Asdia while one deleafing cycle and bi-weekly incision of necrotic spots was done on Adi and Ofir. Implementation of the deleafing technology in the nursery resulted to reduction in ascospore and conidia production. This study suggests that effective deleafing in banana nursery can be an appropriate management method for black sigatoka disease.
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