Management of foliar and soilborne pathogens of cowpea (<i>Vigna unguiculata</i> L. Walp) with two garlic varieties (<i>Allium Sativum</i> A. Linn)

Abstract

White and pink garlic extracts were tested for their antifungal potentials on mycelial radial growth, spores and sclerotial production of Macrophomina phaseolina (Tassi) Goid, Colletotrichum destructivum O gara and Colletotrichum capsici (Syd) Butler and Bisby pathogens of cowpea in vitro. Water or ethanol extracts of common pink and common white garlic varieties were tested at a concentration of 250 ppm while sterile distilled water served as control. In vivo study was based on white garlic extract alone at 0, 50 and 100% concentrations on M. phaseolina and C. capsici. Data were subjected to ANOVA and means was separated at P=0.05. Water extracted white garlic gave over 90% inhibitions of mycelial growth of M. phaseolina and gave higher inhibitions than water or ethanolic pink garlic extracts on all the three pathogens. It is not significantly lower P=0.05 than conventional fungicide benomyl at 0.5 gai/kg. However, in vivo result was phytotoxic to cowpea seeds at 100% concentration of white garlic extract. On cowpea variety TVx 3236, C. capsici inoculated seed germination and pathogen control was 100%, also, M. phaseolina inoculated seeds germination was 100% but there was no pathogen control at 50% garlic extract. In contrast, cowpea variety IT84S-2246-4 seed germination was 77% when treated with M. phaseolina and 100% with C. capsici but reduced pathogen control at 50% garlic extract.

Keywords: Pink and white garlic, fungal pathogens, conventional fungicide, cowpea varieties, germination, phytotoxicity, control

African Journal of Biotechnology, Vol 13(17), 1791-1795