Reaction of a Resistant and a Susceptible Corn Hybrid to Various Southwestern Corn Borer Infestation Levels1

Abstract

AbstractInfestation of corn (Zea maysL.) by the southwestern corn borer [Diatraea grandiosella(Dyar)] can result in substantial losses. Corn genotypes with resistance to leaf feeding damage by the southwestern corn borer have been developed; however, no data on the effectiveness of this resistance in preventing yield and plant height reductions have been reported. To compare the effects of varying infestation levels on a leaf‐feeding‐resistant and a leaf‐feeding‐susceptible corn hybrid, plants in the 10 to 12 leaf stage of growth were infested with 0 to 40 southwestern corn borer larvae per plant in a field study grown on a Leeper silty clay loam (fine, montmorillonitic, nonacid, thermic, Vertic Haplaquepts) in 1982 and 1983. Plants were evaluated for leaf feeding damage, height, and grain yield. Infestation of the susceptible hybrid with 0 to 40 larvae per plant resulted in a linear decline in plant height and yield as infestation level increased. Infestation with 40 larvae per plant reduced yield 39%. Conversely, neither plant height nor yield of the resistant hybrid was significantly reduced at any infestation level. The level of resistance found in the resistant hybrid was, therefore, adequate to prevent losses.