Department of Crop Sciences University of Illinois at Urbana-Champaign

Agronomy Day 2006

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Oldies But Goodies – Weeds That Just Won’t Go Away

Dawn Nordby Dawn Nordby
Extension Specialist- Weed Science IPM
Department of Crop Sciences
dnordby@illinois.edu
217-333-4424
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Reprinted by permission, Copyright © 2006, Farm Progress Companies
figure 2
Reprinted by permission, Copyright © 2006, Farm Progress Companies

Our arsenal of herbicides and tactics to control weeds has changed a lot from the 1950s; however, some of the weeds that gave farmers fits then still are around today. Morningglory, cocklebur, velvetleaf, giant ragweed, and those pesky foxtails can still be found infesting fields across the Midwest and occasionally giving farmers some problems.

There are many reasons for the persistence of these weeds such as seed dormancy, resistance to herbicides, and adaptation to our current farming practices such as a prolonged germination period. Past and current weed management tactics have only targeted what has emerged and not what lies beneath. Soil microbes, earthworms, and insects can play a vital role in weed seedbank persistence and dissipation.

We have recently conducted a survey across Iowa, Illinois, and Indiana encompassing over 150 fields to determine what weeds are escaping our current management programs. We also collected soil samples from every field to determine what the weed seedbank has in store for future generations of farmers. To no surprise, many of these soil samples included morningglory, foxtail and velvetleaf.

Many of today’s concerns focus on weed species that historically have not been common or problematic, but that are now beginning to cause heightened awareness and attention. Weed spectrums can, and often do, change over time and in response to weed management practices, but it’s reasonable to assume that some of the “old familiar” weed species will continue to challenge farmers into the future.

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Reprinted by permission, Copyright © 2006, KING FEATURES SYNDICATE