The importance of Pratylenchus goodeyi on bananas and plantains in the Cameroon Highlands and development of cultural control methods
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Bananas and plantains (Musa spp.) play a vital role in the food security of local populations and contribute to the economies of many developing countries. The Cameroon Highlands are an important production zone, accounting for one third of all Musa spp. produced in Cameroon. Plant parasitic nematodes are a major constraint for Musa production. In the Cameroon Highlands, the nematode Pratylenchus goodeyi can be found in high numbers in Musa roots. Knowledge of the relative importance of each nematode species affecting Musa spp. is imperative when seeking effective management options, prioritising research goals or identifying technology transfer needs. The relative importance of P. goodeyi as a constraint for Musa production in the Cameroon Highlands was therefore examined.
Firstly, the study area was characterized. Interviews were held with 216 farmers of the Cameroon Highlands to better understand their cultivation practices and pest awareness. The survey revealed that Musa spp. are one of the most important crops for a majority of farmers in the Cameroon Highlands. In all fields visited, Musa spp. were planted in mixed cropping systems. At most farms, Musa spp. were primarily infested with P. goodeyi. The most commonly cited Musa production constraints were damage caused by the weevil larvae, toppling and leaf necrosis. Pest awareness was strongly linked to the visibility of the pest. While most farmers were aware of the banana weevil, only few had ever heard of a nematode before.
Secondly, a field experiment was set up to examine the damaging potential of P. goodeyi. Three Musa cultivars were planted into an infested field and their growth and production were observed during 830 days. Pratylenchus goodeyi was the main cause of root damage. Higher root damage was associated with reduced yield due to toppling, lengthening of the growth cycle and a failure to establish. Damage observed during this trial was generally higher for the plantain cultivar compared with the two banana cultivars. The plantain was also more susceptible to the combined effects of low soil fertility and nematode damage. This experiment demonstrated that P. goodeyi is capable of causing significant damage to Musa spp. in farmers fields.
Thirdly, the host range of P. goodeyi was evaluated on 12 crops commonly planted by farmers in the Cameroon Highlands. Banana was used as a susceptible reference crop. Beans and maize (cv. CMS 8704) were good hosts of P. goodeyi. Watermelon and onion were intermediate hosts. Maize(cv. Kasaï), taro,okra, Irish potato and sweet potato were poor hosts; while cocoyam and tomato were very poor hosts. These results confirm that P. goodeyi has a narrow host range, but also highlight the importance of validation trials prior to advising crops to farmers, as differences were observed among cultivars of the same crop and with the results obtained in previous studies.
These results suggest that P. goodeyi is a more important constraint to Musa production than previously thought. The importance of Musa spp. for farming households, the low levels of pest awareness and the capacity of P. goodeyi to cause severe yield loss, underscore an urgent need to increase farmer training initiatives in the Cameroon Highlands.