Andrew H. Heggenstaller
Iowa State University
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Featured researches published by Andrew H. Heggenstaller.
Weed Science | 2005
Paula R. Westerman; Matt Liebman; Fabian D. Menalled; Andrew H. Heggenstaller; Robert G. Hartzler; Philip M. Dixon
Abstract To improve understanding of relationships between crop diversity, weed management practices, and weed population dynamics, we used data from a field experiment and matrix models to examine how contrasting crop rotations affect velvetleaf. We compared a 2-yr rotation system (corn–soybean) managed with conventional rates of herbicides with a 4-yr rotation (corn–soybean–triticale + alfalfa–alfalfa) that received 82% less herbicide. In November 2002, a pulse of velvetleaf seeds (500 seeds m−2) was added to 7- by 7-m areas within replicate plots of each crop phase–rotation system combination. Velvetleaf seed, seedling, and reproductive adult population densities, seed production, and seed losses to predators were measured during the next year. Velvetleaf seed production was greater in the 4-yr rotation than in the 2-yr rotation (460 vs. 16 seeds m−2). Averaged over 12 sampling periods from late May to mid-November 2003, loss of velvetleaf seeds to predators also was greater in the 4-yr rotation than in the 2-yr rotation (32 vs. 17% per 2 d). Modeling analyses indicated that velvetleaf density in the 4-yr rotation should decline if cumulative losses of seeds produced in the soybean phase exceeded 40%. Achieving such a level of predation appears possible, given the observed rates of velvetleaf seed predation. In addition, no tillage occurs in the 4-yr rotation for 26 mo after soybean harvest, thus favoring seed exposure on the soil surface to predators. Models that included estimates of seed predation indicated that to prevent increases in velvetleaf density, weed control efficacy in soybean must be ≥ 93% in the 2-yr rotation, but could drop to 86% in the 4-yr rotation. These results support the hypothesis that diverse rotations that exploit multiple stress and mortality factors, including weed seed predation, can contribute to effective weed suppression with less reliance on herbicides. Nomenclature: Velvetleaf, Abutilon theophrasti Medicus ABUTH; alfalfa, Medicago sativa L.; corn, Zea mays L.; soybean, Glycine max (L.) Merr.; triticale, Triticosecale spp.
Weed Science | 2006
Paula R. Westerman; Matt Liebman; Andrew H. Heggenstaller; Frank Forcella
Abstract To better understand seed predation and enhance weed seed losses in arable fields, we developed a conceptual model that integrates seed dispersal, seed burial, and seed demand, the three processes that determine the dynamics of summer annual weed seeds on the soil surface in late summer and autumn. Published and unpublished experimental data were used to parameterize a simulation model for a number of crop–weed combinations. Sensitivity analyses of models for giant foxtail in corn and soybean indicated that factors related to seed availability were more important in determining overall seed losses due to predation than those related to seed demand. Delaying harvest date and destroying unshed weed seeds collected at harvest emerged as promising strategies to reduce seed input into the seed bank. The role of plant debris in hiding weed seeds from predators was ambiguous and requires further investigation. Estimates of overall seed losses due to predation based on model simulations in various crops and cropping systems indicated that weed seed predation could serve as an important tool in ecological weed management. Nomenclature: Giant foxtail, Setaria faberi Herrm. SETFA; corn, Zea mays L.; soybean, Glycine max (L.) Merr.
Journal of Applied Ecology | 2006
Andrew H. Heggenstaller; Fabian D. Menalled; Matt Liebman; Paula R. Westerman
Agriculture, Ecosystems & Environment | 2006
Megan E. O’Rourke; Andrew H. Heggenstaller; Matt Liebman; Marlin E. Rice
Agronomy Journal | 2008
Andrew H. Heggenstaller; Robert P. Anex; Matt Liebman; David N. Sundberg; Lance R. Gibson
Agronomy Journal | 2008
Matt Liebman; Lance R. Gibson; David N. Sundberg; Andrew H. Heggenstaller; Paula R. Westerman; Craig Chase; Robert G. Hartzler; Fabian D. Menalled; Adam S. Davis; Philip M. Dixon
Crop Science | 2007
Robert P. Anex; Lee R. Lynd; Mark Laser; Andrew H. Heggenstaller; Matt Liebman
Archive | 2009
Andrew H. Heggenstaller; Kenneth J. Moore; Matt Liebman
Archive | 2008
Andrew H. Heggenstaller
Archive | 2007
Matt Liebman; David N. Sundberg; Jaclyn K. Borza; Andrew H. Heggenstaller; Craig Chase