Use of indigenous plant extracts for the protection of mechanically injured sweet potato [Ipomoea batatas (L.) Lam] tubers

Abstract

Protection of mechanically injured Sweet potato (Ipomoea batatas (L.) Lam) tubers from fungal rot with extracts of some indigenous plants namely; Alchornea cordifolia, Annona muricata, Allium sativum. Gacinia cola and Zingiber officinale was investigated. The following fungi; Aspergillus flavus link Ex fr, Aspergillus niger Van Tieghern, Botryodiplodia theobromae (Pat) novel, Fusarium solani Mart Sacc. Desm, Fusarium oxysporum schlecht and Rhizopus stolonifer Ehrenb ex link were isolated from rotted tissues and found to cause rots of sweet potato tubers. The water extracts of these plants suppressed fungal growth in culture and reduced rot development in the tubers when inoculated with the fungi. The highest percentage inhibition of 73.33% was obtained with the use of Z. officinale extract on F. oxysporum while A. sativum extract caused 6.91% inhibition of F. solani. Rot development caused by B. theobromae was reduced by 45.64% with the use of A. cordifolia while Z. officinale gave the highest inhibition of 70.99% on R. stolonifer inoculated tubers. Key words: Plant extracts, rot fungi, rot inhibition, sweet potatoes.