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 diseasesof 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, (IITA), Ibadan, were used for the study. Results of the investigation showed that disease incidence for leaf spot were significantly (P>0.05) more effective using neem seed extract (28.71 %), than neem leaf extract (29.84%), and decis (31.37%). 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 (54.84%) gave a lower incidence of leaf curl disease 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 ground were reduced using neem seed extract and decis. Yield result of the study proved that neem leaf extract (5.00 kg/ha) was less effective on the yield of groundnut when compared with the plots treated with neem seed extract (5.296 kg ha) and decis (5.80 kg ha).