ABSTRACT

 Field trial was conducted at the Western farm of the Michael Okpara University of Agriculture, to evaluate the efficacy of neem seed, neem leaf extract and the synthetic pesticide decis, on the severity of leaf spot, leaf curl and wilt disease of groundnut. The experiment was laid out in a Randomized Complete Block Design with four treatments replicated three times. Fresh neem leaves and dried seed extract were prepared using the hot water method of extraction. The experimental plots were sprayed using 100ml of plant extract used at weekly intervals, starting from the fourth week after planting before the disease was noticed in the filed. Diseases observed were assessed based on their symptoms, at 2 - weekly intervals, starting from 4 weeks after planting. Seeds of groundnut variety RMP 91, obtained from International Institute of Tropical Agriculture, (UTA), Ibadan, were used for the study. Results of the investigation showed that the incidence of leaf spot disease of groundnut (RMP 91) reduced significantly (P<0.05) when neem seed extract (28.71%), neem leaf extract (29.84%), and decis (31.37%) were used. Severity of the leaf spot disease were, however, significantly reduced on those plots treated with neem seed extract (6.9) when compared with other treatment, neem leaf- extract (7.16) and decis (7.53). Neem leaf - extract gave a lower incidence of leaf curl disease (54.84%) than neem seed-extract (60.53%) and decis (67.80%). Disease severity for leaf curl were effectively controlled using decis (5.36) and this was followed by neem seed-extract (6.53) and neem leaf-extract (6.76). Percentage incidence of the wilt disease of groundnut were reduced using neem seed extract and decis. Yield result of the study proved that plots treated with neem leaf extract was less (5.00 kg/ha) when compared with the plots treated with neem seed extract (5.296 kg ha) and decis (5.80 kg ha).