VARIATIONS IN THE SUSCEPTIBILITY OF SOME LOCAL AND IMPROVED MAIZE (Zea mays L.) GENOTYPES TO STEM BORER INFESTATION IN A SUB-HUMID ENVIRONMENT

Abstract

Thirty maize varieties were evaluated for susceptibility to natural infestation of the stem borers for resistance to stem borers in the early and late seasons of 2012 at the Teaching and Research Farm, Federal University of Agriculture, Abeokuta. Borer-resistant variety - BR9928-DMRSR C1 - was used as the check, while resistance was established based on the population of the stem borers and level of damage induced by the insects on the maize plants. Among the stem borers, S. calamistis population was the largest both in the stem and cob during the early season, while that of B. fusca was the largest in the late season. Chilo partellus population was the least in the early season, and was not observed in the late season. Using resistance indices, local varieties: TZM 99, TZM 212 and TZM 137 were found susceptible. Borer-resistant accession, BR9928-DMRSR C1, had significantly lower larval population in the stem and percentage tunneled stem of 0.0 and 0.32% during the early while during late seasons, it had 1.0 and 0.62% respectively. However, the performance of the improved varieties: SUWAN 1, DMR LSR Y, 2000SYN EE-W STR, TZBR ELD-3 C5, TZE[1]WDTSTR C4 and EVDT-Y2008STR had statistically similar (p

<0.05) damage to the borer-resistant variety and were classified highly resistant. It is recommended that BR9928- DMRSR C1, SUWAN 1, DMR LSR Y, 2000SYN EE-W STR, and TZBR ELD-3 C5, which were found highly resistant to the stem borers, and produced statistically similar high grain yield, should be cultivated in stem borer-infested areas. >