Field trails were conducted to evaluate the economics of controlling cercospora leaf spot of groundnut using different fungicides. The experiments were laid out in a strip plot design 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. Four fungicides namely: Benlate 50 WP, Trimangol 80 WP, Bentex T, and Ridomil 72 WP were applied as foliar sprays at three spray regimes while the control was left untreated. The application of the fungicides led to 20–50% reduction in the disease incidence and 15–22% reduction in disease severity and gave higher yield of seed and haulm than the control. The cost-benefit analysis revealed positive returns per hectare from the use of the fungicides for the control of disease in the study area. Application of Bentex T, for instance, gave 78.13% seed yield increase over the control which translated into a mean (two years) net profit of N52,267.50, N90,905.00 and N138,755.00 Nigerian Naira for one, two and three sprays, respectively, equivalent to $522.675, $909.05 and $1,387.55 per hectare. Even the least effective of the fungicides (Trimangol 80 WP) gave seed yield increase of 62.74% over the control which translated into a mean (two years) net profit of N41,287.50, N68,082.50 and N93,995.00 equivalent to $412.88, $680.83 and $939.95 per hectare for one, two and three sprays, respectively. Three sprays gave 115. 76% increase of yield over one spray and 39.35% yield increase over two sprays. These returns are attractive particularly to the farmers in the study area who grow the high yielding Ex-Dakar groundnut variety which is susceptible to cercospora leaf spot.

The efficacy of Benlate 50 WP (benomyl), Bentex T (benomyl + thiram), Ridomil 72 WP (metalaxyl) and Trimangol 80 WP (maneb) applied as foliar spray in the control of cercospora leaf spot of groundnut in the sudan savanna of Nigeria was evaluated during the 2002 and 2003 cropping seasons. Three spray regimes (once, twice and thrice per season) were evaluated. Strip plot design with three replications was used in setting up the experiments. Ex-Dakar, a cercospora leaf spot susceptible groundnut variety was used as planting material. All the four fungicides significantly reduced the incidence and severity of cercospora leaf spot in both seasons. However, the application of Bentex T significantly better reduced the incidence and severity of the disease than the other fungicides. This was followed by application of Benlate 50 WP. Ridomil 72 WP and Trimangol 80 WP which gave moderate control of the disease. Three sprays with fungicides gave better control of the disease than one or two sprays in the season. The highest seed yield of 1 716 kg/ha and 2 263 kg/ha in 2002 and 2003, respectively, were obtained following treatment with Bentex T. The lowest yield of 962 kg/ha and 1 270 kg/ha in 2002 and 2003, respectively, were recorded from the control plots. Also the highest seed yield of 2 028 kg/ha and 2 672 kg/ha in 2002 and 2003, were obtained following three sprays compared to 939 kg/ha and 1 239 kg/ha in 2002 and 2003, respectively, for one spray in the season. The highest haulm yield of 6 131 kg/ha and 6 722 kg/ha in 2002 and 2003 was recorded from plots treated with Bentex T compared to 4 752 kg/ha and 5 166 kg/ha in 2002 and 2003, respectively, obtained from the control. Haulm yield of 6 355 kg/ha and 7 027 kg/ha in 2002 and 2003 were obtained following three sprays compared to 5 088 kg/ha and 5593 kg/ha in 2002 and 2003, respectively, recorded for the control. Bentex Tor Benlate 50 WP could be used to reduce the effect of cercospora leaf spot and improve groundnut production in the sudan savanna of Nigeria.