![Sample our Environment & Agriculture journals, sign in here to start your access, latest two full volumes FREE to you for 14 days]({"type":"image" , "src" : "/sda/5934/TOC-Subject-Sample-2021-Environment-Agriculture.jpg"})
ABSTRACT
Common bacterial blight disease of cowpea, caused by Xanthomonas axonopodis pv phaseoli, has been identified as the most important biotic constraint to cowpea production worldwide. Continuous and indiscriminate application of chemical pesticides has necessitated the search for an environment friendly method of control. Azadirachta indica (neem), Acalypha wilkisiana (red acalypha) and Carica papaya (pawpaw) extracts were field-tested against common bacterial blight disease. The experiment was laid out as a randomized complete-block design (RCBD) with three replicates. Cold extracts of 6.67% concentration of the plant leaves were sprayed on cowpea (variety ‘Ife brown’) foliage. Streptomycin sulfate of 0.2% concentration was applied as a positive control and sterile distilled water as a negative control. Incidence of common bacterial blight ranged from 20.00 to 43.74% and severity from 1.02 to 2.00 on a 1–6 scale, where 1 = no symptoms of common bacterial blight and 6 = necrotic lesions on more than 75% of the leaf area. A combination of extracts of pawpaw, neem and red acalypha reduced disease incidence by 73.68% and improved yield by 1.58 tons/ha (a 73.49% increase) compared with untreated control. Azadirachta indica, Acalypha wilkisiana and Carica papaya extracts, both singly and in combination (Pawpaw + neem + Acalypha, Pawpaw + neem, Pawpaw + Acalypha and neem + Acalypha), reduced incidence and severity of common bacterial blight disease and increased yield of cowpea. Thus, these plant extracts could serve as viable alternative to synthetic chemicals to control Xanthomonas-caused diseases in cowpea.