Composition and management of weed flora in smallholder farmers’ fields in Swaziland

The weed flora in smallholder farmer’s fields and the potential arable farmers have on their weeds in Swaziland were investigated in the 2015/2016 cropping season. The study was conducted in five agro-ecological zones, 117 fields and 99 farmers were interviewed. All together 34 weed species from 18 families were identified. Using the Shannon’s index, the Highveld of Swaziland had the highest species diversity as compared to the other regions with the Lowveld having the lowest diversity. With Jaccard’s index for comparing communities, the Highveld and Upper Middleveld had the highest number of species in common as compared to the Highveld and the Lowveld which had the least. Commelina benghalensis (L.) was the most abundant weed species in the Highveld and Upper Middleveld with Acanthospermum hispidum (DC) being the most abundant in the Lower Middleveld, Richardia scabra (L.) in the Lubombo and Eleusine indica (L.) Gaertn in the Lowveld, respectively. The second part of the study involved semi structured interviews where farmers were asked to identify and characterize weeds that are most problematic, aggressive and difficult to control. Cynodon dactylon (L.) Pers. was found to be the most problematic and difficult to control whilst Richardia scabra (L.) and Xanthium strumarium (L.) were the most aggressive weeds. From this study, it was noted that some weed species (Corchorus olitorius L., Amaranthus hybridus L. and Bidens pilosa L.) were among weeds that were left unweeded due to their contribution to the farmer’s diet. It was also noted that 82% of the farmers practiced post-harvest weed management whilst 80% managed their headlands. Weed surveys remain integral to identifying possible problematic weeds and weed population shifts and directing research towards new or improved control measures.