Many traditional healing systems are based on natural biological resources, and there is a general shift in most parts of the world towards natural medicine, with direct implications on the demand and supply of medicinal plants. This review highlights the economic importance of medicinal plants, their contribution to healthcare systems, and potential opportunities for rural economic development through cultivation. A systematic literature review with specific search terms related to medicinal plants was used to collect scientific and non-scientific information from peer-reviewed literature and grey literature databases. The findings indicate that trade in medicinal plants is increasing, and although they are considered minor crops compared to major food crops, their value is among the highest in the list of traded plants globally. The trade also serves as a revenue source for many rural livelihoods, with women playing a significant role. Medicinal plants contribute to primary health care in many developing countries, and they are also an essential source of modern drug discovery. Cultivation of medicinal plants offers emerging rural farmers an opportunity to grow these plants as new and alternative crops, thus reducing unsustainable wild harvesting and competition with established commercial farmers who mostly focus on food crops. Furthermore, medicinal plant cultivation should be promoted as one of the options for local economic development and sustainability through job creation, the revival of the rural economy, and income generation for small businesses, such as the transport businesses, involved in the value chain. Land accessibility, financial resources, and direct market access for rural communities can elevate their contribution to the industry. Formalisation of the lower levels of the medicinal plant trade is also recommended. Significance: Cultivation is a viable option for biodiversity conservation of medicinal plants and ensuring a goodquality supply of plant materials. Cultivation of medicinal plants – a source of natural products used in product development – can contribute to job creation, income generation, and rural economies in developing countries. This review underlines the importance of medicinal plants in product development, the contribution of the industry to economies of different countries, and the potential for cultivation.

Cowpea [(Vigna unguiculata(L.) Walp)] is highly susceptible to the emerging guava root-knot nematode,Meloidogyne enterolobii, with available management options being limited due to the withdrawal of effective fumigant nematicides from the agrochemical markets. Filamentous fungi, available as Biocult (a.i.Glomusspecies +Trichoderma asperellumLieckf and Nirenberg) and Nemafric-BL phytonematicide (a.i. cucurbitacin B) each improves plant growth and suppresses nematode population densities. However, when filamentous fungi like Biocult are combined with other biocontrol agents, the combined effects either have synergestic or antagonistic effects on the test variables. The combined effects of Biocult and cucurbitacin phytonematicides on plant growth and nematode suppression remain undocumented. The objective of this study was therefore to determine the combined effects of Biocult and Nemafric-BL phytonematicide on growth of cowpea var. Eureka and suppression ofM. enterolobiipopulation densities. Eureka was subjected to the effects of the two products in a 2 × 2 factorial experiment on a field infested withM. enterolobii. At harvest, the interaction of Biocult and Nemafric-BL phytonematicide was highly significant (P≤ 0.01) on plant and nematode variables, with a two-way table used to assess the findings. Relative to untreated control, Biocult alone increased plant growth variables from 15 to 74%. Similarly, NemafricBL phytonematicide increased plant variables from 14 to 61%, whereas the combined effects significantly increased dry shoot mass (19%) and dry harvestable leaf mass (21%), but did not have significant effects on plant height and stem diameter. Relative to untreated control, Biocult alone reduced nematode eggs in root (80%), J2 in root (84%) and J2 in soil (53%), whereas the combined relative effects of the two products did not have significant effects on nematode population densities. In conclusion, Biocult and Nemafric-BL phytonematicide had antagonistic effects on growth of cowpea and suppression ofM. enterolobiipopulation densities and therefore, should be used separately in cowpea production.

Potato (Solanum tuberosum) cultivars are highly susceptible to the root-knot (Meloidogyne spp.) nematodes, with the preferred nematode management strategy being rotation using nematode-resistant crops. Most commercial potato- producing farmers prefer high-yielding, but low-input leguminous crops for use in potato crop-rotation systems intended to manage Meloidogyne spp. A study was conducted to screen 11 commonly used dry bean (Phaseolus vulgaris) cultivars in potato rotation systems for managing population densities of Meloidogyne species. Three screening trials, each for M. javanica, M. incognita race 2 and M. incognita race 4, were conducted under greenhouse conditions. After validation in time, at 56 d after inoculation, the reproductive potential values of Meloidogyne spp. on test dry bean cultivars suggested that the cultivars were hosts, except for the cultivar ‘Kleinwit’, which was a non-host to M. incognita race 2 and M. incognita race 4, but host to M. javanica. In conclusion, except for ‘Kleinwit’, most dry bean cultivars used for managing Meloidogyne species in potato–dry bean crop-rotation systems in South Africa are hosts and are therefore not fit for the intended purpose since host plants promote the build-up of nematodes. In addition, ‘Kleinwit’ should be used with caution because it was host to M. javanica.