Reaction of Cowpea Genotypes to Bacterial Blight (Xanthomonascampestrispv. Vignicola) Disease in Ghana

The productivity of cowpea is constrained by a variety of biotic and abiotic factors. Insects, fungi, bacteria, parasitic plants and nematodes are the major biotic stresses, and drought, salinity and heat are among the major environmental limitations to cowpea productivity. Among the diseases, bacterial blight caused by Xanthomonasaxonopodispv. Vignicola (Burkholder) Dye is one of the diseases posing a serious challenge to cowpea production in Ghana and the rest of Africa where the crop is usually cultivated. The objective of the study was to identify Cowpea genotype that are resistant to bacterial blight. Thirty-one cowpea lines collected from research institutions (SARI-Nyankpala, PGRRI-Bunso, IITA-Kano-Nigeria and CRI-Kumasi) composed of landraces and released varieties were used for the trial. These were grown in polybags of 20 plants per accession in a Completely Randomize Design with four replications. The plants were inoculated with X. vignicla cultures when the plants were three weeks old. Results indicate that 64.5% of the plant total was moderately resistant, 22.6% were resistant and 12.9% were susceptible. The genotypes GH4025 and GH2347 were found to be promising resistant genotypes. The most pathogenic of all the strains was Ohawu 1 followed by Nyankpala 1 and CRI 2 respectively. Thermos resistant genotypes GH4025, GH4327 and IT97K-1069-6.exhibited higher level of resistance in all the three strains and the genotypes TVu7778, GH7889, IT84S-2246-4 and GH7225 exhibited similar levels of susceptibility to the three strains of the bacterial blight isolates. However, bacterial blight symptoms were observed on leaves inoculated with 108 cfu g-1 bacterial suspensions.