Pesticidal and Medicinal Value of Turmeric and Ginger in Tanzania and Their Antifungal Activity against Phytopathogens

Abstract

Use of synthetic pesticides to manage crop pests has had a toll on human health, environmental safety and farmer’s income creating a need for alterna tive crop protection strategies. Botanical pesticides have been reported to be effective in managing crop pests, and a number of them have been formulated and commercialized. This study was conducted in North-Eastern Tanzania to establish the pesticidal and medicinal value of turmeric (Curcuma longa) and ginger (Zingiber officinale). Purposive sampling was adopted to select and in terview 167 respondents drawn from farmers, traders, pharmaceutical shops, agro-shop operators and consumers of turmeric and ginger. Ginger and tur meric rhizomes were also collected for extraction, antifungal assay and bio chemical analysis. Results showed that majority of the respondents were aware of the medicinal value of ginger and turmeric, with 59.5% having used the plants to treat respiratory related infections and healing skin surface and in ternal wounds. About 14% of farmers were aware of and had used aqueous botanical preparations from neem, moringa and Tephrosia to manage insect pests. Only 2.7% of farmers had used ginger powder as a protective insecticide on stored grains. Ginger and turmeric rhizome extracts showed high antifun gal activity against Pythium (83% - 95%), Fusarium oxysporum f. sp. lycoper sici (34% - 52%) and Alternaria solani (38% - 53%). A GC-MS analysis of gin ger and turmeric extracts showed presence of α-zingiberene, β-sesquiphellan drene, α-farnesene, ar-curcumene, α-copaene, ar-tumerone and curlone. This study recommends that ginger and turmeric extracts be considered for devel opment of a botanical pesticide and especially for management of damping off diseases.