Second‐brood Damage by Southwestern Corn Borer in a Corn Diallel Cross1

Plants from reciprocal diallel crosses among nine (seven resistant and two susceptible) genotypes of corn (Zea mays L.) were evaluated for damage by second‐brood southwestern corn borer (Diatraea grandlosella Dyar). All plants were infested with southwestern corn borer eggs at silking time, and the extent of damage to the plant was determined 35 days later. Mean squares for maternal, reciprocal, and specific combining ability were small and generally not significant. Selections from populations 44# and 45# contributed a higher level of resistance to their crosses than did the other three resistant parents. The resistant ✕ resistant crosses had 36% fewer tunneled plants than the susceptible ✕ susceptible cross, and these tunneled plants had only 56% as much damage.