Screen-house evaluation of some plant extracts for antiviral properties against cowpea aphid-borne mosaic genus potyvirus in cowpea, Vigna unguiculata l. (walp.)

The purpose of this work is to assess the antiviral properties of ten plant extracts against Cowpea aphid-borne mosaic Potyvirus (CABMV) in Vigna unguiculata var. Crude extracts were obtained from leaves and bulbs of Allium cepa, cloves of A. sativum, leaves of Artemisia annua, leaves and seeds of Azadirachta indica, leaves of Hyptis suaveolens, leaves and seeds of Moringa oleifera and rhizome of Zingiber officinale using water. The virus inoculum was prepared using the extract from the various plant sources and used to mechanically inoculate the test plants of V. unguiculata var. Ife brown in the screenhouse. Infection of test plants by virus was confirmed by the Double Antibody Sandwich Enzyme-Linked Immunosorbent Assay (DAS-ELISA). All the extracts showed varying degrees of inhibition of CABMV on the test plants. However, there was high significant difference between extract from onion leaf and the other treatments. Onion leaf had the lowest virus incidence (19.9%) while others had incidence values ranging from 53 to 77%, with the highest being moringa leaf. Percentage inhibition of onion leaf was 73% compared to other extracts with neem seed having the least inhibition. This study shows that the antiviral properties of onion leaf, Artemisia leaf and onion bulb compare favourably with those of Garlic cloves, Hyptis leaf, Ginger rhizome, Moringa leaf and seeds. The use of onion leaf and bulb in managing CABMV in cowpea plants should be explored.