Date of Award
Doctor of Philosophy
Adult phenology, relative abundance, and reproductive status of feral stalk borer moths, Papaipema nebris (Gn.), were investigated from 1980 to 1983, using collections from blacklight traps. Males constituted 89.2% of trap collections versus 10.8% female moths. In all four years, the first moth was collected between 10 and 21 August and 50% flight occurred between 8 and 14 September. Multiple matings by female moths were common, with the mean number of spermatophores being 2.0, but total numbers ranging from 0 to 7 spermatophores per female. Although the dates of flights in this study agreed with Illinois dates, the thermal-unit model proposed in previous literature failed to predict satisfactorily adult phenology in Iowa, suggesting that factors other than CDD accumulations influence dates of adult emergence and subsequent flights;Additionally, effects of stalk borer damage on 2- to 4-leaf-stage field corn was studied to characterize the plant damage syndrome and subsequent yield losses associated with larval infestations. Damage was categorized as uninfested, leaf-feeding only, or dead-heart (whorl death). Yields of stalk, grain, cob, and total dry weights were monitored from both damaged plants and plants growing adjacent to damaged plants. Yields of plants sustaining leaf-feeding damage alone were not significantly different from yields of uninfested plants. Dead-heart damaged plants, however, produced yields significantly reduced from yields of all other plants except for the parameter of stalk dry weight. Lack of reproductive synchrony with healthy plants seemed to cause the reduced yields produced by plants with dead-heart damage. In all probability, this loss of synchrony resulted in greatly diminished pollination and increased numbers of barren stalks for plants sustaining injury. In the absence of mortality, yield compensation by healthy plants growing near damaged plants was not observed. Damage from larval infestations of corn plants growing adjacent to brome grass terraces was most severe in the first row of corn bordering the terrace and gradually decreased in severity with distance away from the terrace.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
Wayne Charles Bailey
Bailey, Wayne Charles, "Stalk borer phenology, damage syndrome, and yield loss potential in field corn " (1985). Retrospective Theses and Dissertations. 7817.