No abstract

The efficacy of different rates of abamectin for the control of root knot nematodes in tobacco soil-based seed beds was evaluated in this study. Different incorporation methods of abamectin in the soil were also evaluated. A combination of 45 ml worked into the soil to a depth of 20 cm using hoes was effective in controlling root knot nematodes. The efficacy was comparable (p = 0.05) to methyl bromide and 1.3 D. The other treatments evaluated did not give control and were comparable to the untreated control. Based on the results, abamectin can be a suitable replacement for methyl bromide for root knot nematode management in the tobacco seedbed.

Radopholus similis is the most destructive plant parasitic nematode in banana production systems. A glasshouse experiment was carried out to evaluate the effect of legume intercrops on R. similis population and damage level in banana. A trial was laid out in a randomised complete block design with five treatments and five replications. The treatments were banana/cowpea (Vigna unguiculata) intercrop, banana/sunn hemp (Crotalaria juncea) intercrop, sole banana, sole banana with nematicide (Fenamiphos) and sole cowpea. Sunn hemp intercrop was suppressing R. similis population densities and reduced banana root damage the most compared to tested treatments. The legume intercropped banana plants had a significantly higher fresh root mass as the sole-cropped banana with nematicide while the solecropped banana without nematicide had significantly lowest fresh root mass. Sunn hemp and cowpea legumes are recommended for adoption by smallholder banana farmers as alternatives to nematicide use.

Plant-parasitic nematodes are economically important pests of banana (Musa spp.) and compromise its productivity. Controlling nematode populations and good agronomic practices are prerequisites for a good yield. A survey of farmers in the Rusitu Valley, Zimbabwe, was conducted to assess their current banana production practices and knowledge of plant-parasitic nematodes associated with banana. Respondents were selected using systematic sampling from three wards. Most farmers (61.9%) grew bananas as a monoculture, and 38.1% intercrop banana with other crops. All the farmers neither rotated banana with other crops nor practiced pest and disease control measures, and only 11.4% apply a fertiliser to their banana crops. Most (82.9%) farmers in Rusitu Valley had little or no knowledge of plant-parasitic nematodes that damage bananas. Sound extension programme in Rusitu Valley should educate farmers on the importance of managing plant-parasitic nematodes and using better banana crop production practices.

SUMMARYNematode infestation in Sub-Saharan Africa's (SSA) cropping systems, worsened by poor crop rotations, is a major factor contributing to limited utilisation of applied nutrients and water, leading to low maize (Zea mays L.) yields particularly on sandy soils. The effects of nematode infestation on maize productivity were evaluated under conservation agriculture (CA) on granitic sandy soils in sub-humid smallholder farms of Goromonzi district of Zimbabwe. Four treatments were tested for three seasons on six smallholder farmers’ fields in a randomised complete block design, each farm being a replicate: fenamiphos 40EC (a commercial synthetic nematicide), lime + fenamiphos 40EC, lime and an untreated control. Results of the study showed that independent application of fenamiphos 40EC and lime significantly reduced plant parasitic nematode infestations in maize roots by more than 10 times those present in the untreated plots while maize yield also increased significantly. Yield increase from fenamiphos and lime applications amounted to 53 and 42% respectively, compared to the untreated controls. Maize yield was negatively correlated with density of Pratylenchus spp. nematodes. Nematode management strategies involving fenamiphos 40EC or lime could significantly reduce maize yield losses in maize-based smallholder farming systems of SSA under CA. It was more economical to use fenamiphos than lime to control nematodes.