Submitted to: Weed Science Society of America Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 5, 2004
Publication Date: February 7, 2005
Citation: Williams, M.M., Boydston, R.A. 2005. Canopy variation and wild proso millet suppressive ability among three sweet corn hybrids [abstract]. Weed Science Society of America. 45:57. Technical Abstract: Sweet corn (Zea mays L.) production utilizes a wide range of crop phenotypes and previous research suggests cultivar selection is one of the more important cultural practices in reducing weed growth. Using three morphologically-divergent sweet corn hybrids, field studies were conducted to compare canopy development and quantify wild proso millet (Panicum miliaceum L.) suppressive ability. To expand inference space of this work, sites were selected in major domestic sweet corn production regions, including near Prosser, WA and Urbana, IL. A split-plot experimental design was used; with commercially-available hybrids ('Spirit', 'WH2801', 'GH2547') plus a weedy monoculture assigned to main plots and four densities of regionally-adapted wild proso millet populations established in subplots. In crop monoculture plots, leaf area and intercepted photosynthetically active radiation (PAR) were determined throughout the season, and near the R1 growth stage, vertical leaf area distribution was characterized. Wild proso millet shoot growth and fecundity were also determined. More favorable conditions for sweet corn growth were observed in WA, compared to IL. Leaf area index and green ear yield averaged 53 and 34% higher, respectively, in WA than in IL. On the contrary, wild proso millet grew better in IL than WA, with 76% greater maximum shoot biomass in weedy monoculture plots at crop harvest. 'WH2801' and 'GH2547' had 25 to 58% greater per plant leaf area than 'Spirit', with relatively more leaf area distributed higher in the canopy. 'WH2801' and 'GH2547' intercepted more PAR late in the season, although this observation was more obvious in IL than WA. All hybrids suppressed wild proso millet growth, although 'WH2801' and 'GH2547' reduced shoot biomass to a greater extent than 'Spirit'. Improved weed management systems for sweet corn may exploit variation in weed suppressive ability among crop phenotypes, however the stability of relative weed response to crop phenotype requires further study.