Effect of Southwestern Corn Borer Feeding on Maize
1974
The extent of damage to corn (Zea mays L.) caused by infestation with southwestern corn borers (Diatraea grandiosella Dyar) was determined. Corn hybrids were manually infested with corn borer egg masses to simulate a uniform heavy natural infestation. First-brood larval feeding significantly reduced plant height by an average of 16 cm over the 2 years of the test. Significant yield losses of 20 and 9% occurred from first- and second-brood damage, respectively. On plots infested with both broods, yields were reduced 29%. Reduced kernel weight or number of ears produced did not account for the total yield losses that were obtained for different borer treatments. Therefore, we concluded that a considerable portion of the yield reductions caused by southwestern corn borer feeding must be a reflection of the reduction in the number of kernels produced per plant. The magnitude of the yield losses caused by this insect as shown in these tests certainly justifies a breeding program to develop hybrids resistant to the southwestern corn borer. Because first-brood feeding caused a higher percentage of yield losses, a concentration of initial effort on breeding for leaf-feeding resistance seems logical.
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