Utilisation of botanicals for the management of pests and diseases affecting crops in sub-Saharan Africa: A review

In sub-Saharan Africa, most food crop losses are caused by pests and diseases, prompting small-scale farmers to explore the use of botanicals as an environmentally friendly, accessible, and affordable alternative. This review presents a critical appraisal of current trends in the use of botanicals to manage crop pests and diseases in sub-Saharan Africa. A systematic search (covering January 2010 until June 2023) for eligible studies was done by exploring different databases, which yielded 13 eligible studies. An inventory of 177 plant species belonging to 54 families was recorded as botanicals used to control 28 pests and 15 crop diseases. Azadirachta indica A.Juss, Allium cepa L., and Allium sativum L. were the top-cited plants. The families with the highest reported plants were Fabaceae (27), Asteraceae (18), Solanaceae (14), and Euphorbiaceae (10). In terms of life form, the recorded plants were shrubs (40%), trees (38%), and herbs (22%). The plants were mainly used to manage pests and diseases affecting Brassica oleracea L., Solanum lycopersicum L., Zea mays L., Spinacia oleracea L., Brassica oleracea var. sabellica, and Phaseolus vulgaris L. A total of 14 plant parts were recorded, with the leaves (34%) and stem (15%) being the dominant parts used. In most cases, the preparation routes were unspecified (51%), which was followed by decoction (14%) and infusion (14%). The major method of administration was topical (55%), while approximately 39% of reports were unspecified. The pests consisted of vertebrates (28%) and invertebrates (72%) while the three (3) disease categories included fungal (77%), bacterial (17%), and viral (6%). The review revealed an ongoing dependence on the use of botanicals. However, extensive studies must be conducted that apply and adhere to good practice associated with ethnobotanical field surveys. This will aid in generating a comprehensive inventory of botanicals with potential for environmentally friendly pest and disease management.