Cost-benefit of using some plant extracts in controlling cercospora leaf spot of groundnut in the Sudan savanna of Nigeria

Abstract

Field trials were conducted to evaluate the economics of controlling cercospora leaf spot of groundnut using different plant extracts. The experiments were laid out in a completely randomized block design (CRDB) with three replications at the Teaching and Research farm of the Department of Crop Protection, University of Maiduguri, Sudan savanna of Nigeria during the 2002 and 2003 cropping seasons. Five plant extracts, namely, neem seed, garlic clove, onion bulb, ginger rhizome and pawpaw leaf extracts and a fungicide ridomil were applied as foliar sprays while the controls were left untreated. The application of the plant extracts led to about 3–10% reduction in the disease incidence and 10–15% reduction in disease severity and gave higher seed and haulm yields than the control. Ridomil gave about 16% reduction in disease incidence and 19% reduction in disease severity. The cost-benefit analysis revealed positive returns per hectare from use of the plant extracts for controlling the disease in the study area. Application of neem seed extract, for instance, gave 43.82% seed yield increase over the control which translated into a mean (two years) net profit of N198 730.56 Nigerian Naira equivalent to $1987.31 per hectare. Even the least effective of the plant extracts (ginger rhizome) gave seed yield increase of 24.17% over the control which translated into a mean (two years) net profit of N167 247.00 equivalent to $1672.47 per hectare for the two seasons. The control gave mean net profit of N134 121.21 equivalent to $1341.21 per hectare which is lower than those realized from the plant extracts. The profit from the sell of haulms which is an additional income to the farmer amounted to N50 944.56, equivalent to $509.45 per hectare following application of neem seed extract. These returns are attractive particularly to the farmers in the study area who grow the high yielding, cercospora susceptible Ex-Dakar groundnut variety.