Parameters, Interrelationships with Yield and use of Carbofuran to Control Stem Borers in Maize (Zea mays l.) at Makurdi in the Nigerian Southern Guinea Savanna

Early and late crops of flint, pop and sweet maize (Zea mays L.) were sown in field plots laid in randomized complete block design at the Teaching and Research Farm in 2004. Stem borer infestation and damage were assessed both in the plots treated with 1.5 kg carbofuran/ha and in those not treated for stem borer control. The maize types, as subplot treatments, and carbofuran application vs no application, as main plot treatments, were replicated four times. Borer damage was quantified as percentage dead-heart, bored stems, lodged stems, bored internodes, and as numbers of borer larvae/stem and borer cavities. The damage parameters were correlated with each other and with yield. Busseola fusca Fuller was the most abundant species; borer infestation was 5 times higher in the late than in the early crop and application of carbofuran resulted in 86.8 and 63.5 % control, respectively. Yield loss due to borer damage to the early crop was 14.0%; that for the late crop was 1.5-fold higher. In both crops, maize type exerted no significant effect (P>0.05) on borer damage. Percentage bored internodes was positively and significantly (P < 0.01) correlated with number of bored stems (r = 0.95, early crop; 0.88, late crop), and lodged stems (r = 0.82, early crop; 0.83, late crop). Similarly, bored and lodged stems were positively correlated (r =0.75 and 0.74, respectively in the early and late crop; P < 0.01). Dead-heart was positively correlated with each stem damage parameter; coefficients of correlation were higher for the early than the late crop. All damage parameters were negatively correlated with yield but a robust yield loss predictive model was not found. As such, use of carbofuran against maize stem borers would continue to be prophylactic at Makurdi.