oa African Entomology - Infestation levels 0f banana weevil, Cosmopolites sordidus Germar (Coleoptera: Curculionidae), in banana plants established from treated propagules in Uganda
Spread of banana weevil, Cosmopolites sordidus Germar, occurs primarily through infested suckers used for propagation. The use of clean planting material, from which weevils have been removed by paring and/or hot-water treatment, has been recommended as a culturalcontrol strategy. In this study, two trials were undertaken to quantify the effects of cleaned planting material on the level of weevil and nematode infestation and on plant growth and yield. Treatments included: (1) untreated suckers (controls), (2) pared corms and (3) pared and hot-water-treated corms. Initial weevil populations were lower in plots established with cleaned planting material than in controls. In Trial 1, weevil numbers in pared and pared/hot-water-treated material were lower than in control plots for up to 11 months, whilein Trial 2, plots established from pared and pared/hot-water-treated planting material had lower numbers of the pest for 27 months and 20 months, respectively. Weevil damage levels in controls were 70-200 % higher than in plots cultivated from treated planting material for the entire crop cycle. All treatments had similar levels of weevil damage in the first ratoon. Hot-water treatment afforded excellent nematode control for the duration of both trials. In both trials, treated plants had faster plant maturation rates and lower levels of plant loss due to pests. In Trial 1, 21 % of plants in the control crop were lost to weevils and nematodes compared to 2 % in treated plots. In Trial 2, plant loss to weevil and nematodes was 34 % in controls, 6 % in pared and 2 % in hot-water treatments. Eventual bunch size was similaramong treatments in both trials. However, plots with treated plants provided higher yields as a greater number of bunches was harvested during the course of the study.
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