Weed flora of cashew (Anacardium occidentale L.) in Upper and Lower Casamance: characterization of the flora and level of infestation

Abstract

Cashew is one of the most important cash crop in southern Senegal. However, the productivity of cashew plantations is quite low due to many factors including the problem of weeds. This study aims to contribute to the knowledge of the floristic composition and diversity of weeds in cashew plantation of southern Senegal. In these assessed orchards, 66 weed species belonging to 47 genera and 15 families were recorded. Fabaceae, Poaceae and Malvaceae were the most represented botanical families with respectively 32, 21 and 11% of flora. The highest number of species was recorded in Middle Casamance where 40 species and 31 genera were noted while 37 species and 29 genera were found in Upper Casamance. The evaluation of the ecological value of species (IVI index) revealed that Spermacoce stachydea, Mesosphaerum suaveolens, Andropogon pseudapricus, Mitracarpus hirtus are the most noxious species in cashew plantations. Results also showed that vegetation diversity (Shannon-Wiener and Pielou index) do not differ significantly from a district to another. However, the highest value of Shannon index (H') was recorded in Lower Casamance with 1.34 bit while in Upper Casamance the diversity is on average of 1.11 bit.

Keywords : Cashew plantation, Weeds, Diversity, Infestation, IVI index, Senegal