Relationship of maize tissue pH and resistance to whorl leaf feeding and stalk tunneling by the European corn borer (Lepidoptera: Pyralidae).

A study was conducted to investigate whether pH values of selected maize, Zea mays (L.), tissues could serve as useful screening criteria for resistance to whorl leaf feeding and stalk tunneling by the European corn borer, Ostrinia nubilalis (Hubner). Inbred line CI31A displayed the highest whorl leaf pH and had the least leaf feeding. Over all six maize genotypes, however, only a low level of correlation (P < 0.05, r = −0.35) between whorl leaf pH and whorl leaf feeding was observed. Similarly, in a study of four inbred lines, correlations of leaf sheath and stalk pith pH with amount of stalk tunneling were inconsistent and of low magnitude. When whorl leaf, leaf sheath, and stalk pith pH were determined in four cycles of selection of a maize population which had undergone recurrent selection for resistance to both generations of European corn borer, no significant relationships between pH and cycle of selection were observed. Measurement of pH of these plant parts apparently would not be a useful technique to select genotypes resistant to European corn borer.