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Agronomic Crops Network

Ohio State University Extension

CFAES

C.O.R.N. Newsletter

  1. Poison hemlock (Conium maculatum L.) and wild parsnip (Pastinaca sativa L.) are combined in this report because these invasive non-native weeds are increasingly found growing together in Ohio. However, the defense chemicals of these weeds are very different and have vastly different modes of action. This is important to understand relative to management options as well as medical treatments for exposure to these highly dangerous weeds.

    Putting poison hemlock in perspective

    Author(s): Mark Loux , Author(s): Ted Wiseman , Author(s): Allen Gahler

    Poison hemlock seems to be on everyone’s radar more than usual this year, especially in northern Ohio.  We know that while hemlock has been all over southern Ohio for years, it is continuing to spread northward, where new occurrences and observations of it may be engendering concern in the general public and local government. There have also been comments that it seems “worse than usual” this year in

    Issue: 2021-19

  2. Roughstalk Bluegrass in Cereal Grain and Forage Crops

    Author(s): Richard Purdin , Author(s): Taylor Dill , Author(s): Les Ober, CCA

    There is a new and emerging weed challenging cereal grain and forage producers across the state. Roughstalk Bluegrass has taken root in wheat fields and newly established forage stands. This weed has reached population levels high enough to inhibit the harvest of cereal grains, reduce the quality of forages, and crowd out newly established forages.

    What is it?

    Issue: 2021-18

  3. Distribution of waterhemp and Palmer amaranth in Ohio

    Author(s): Mark Loux

    The maps that accompany this article show our current knowledge of waterhemp and Palmer amaranth distribution in Ohio.  These are based on information from a survey of OSU Extension County Educators, along with information we had from samples submitted, direct contacts, etc.  We still consider any new introductions of Palmer amaranth to be from an external source (brought in from outside Ohio) – hay or feed, infested equipment, CRP/cover/wildlife seedings.  Palmer is not really spreading around the state, and as the map shows, we have had a number of introductions that were immediately reme

    Issue: 2020-18

  4. It’s All About the Weed Seedbank – Part 2: Where Has All the Waterhemp Come From?

    Author(s): Mark Loux

    Weed populations are constantly shifting, in response to the pressure from our cultural and herbicide use practices, and how good our management of weeds is (or isn’t).  Two weeks ago in CORN, we wrote about the apparent decline in marestail in parts of the state, although in subsequent communication we heard fairly clearly that not everyone’s populations had declined yet.  And there is bad news - waterhemp is spreading at a rapid rate, and it’s a considerably more challenging pest than marestail for several reasons.  The question really is – why has waterhemp taken off over the past severa

    Issue: 2019-12

  5. It’s All About the Weed Seedbank – Part 1: Where Has All the Marestail Gone?

    Author(s): Mark Loux

    For the second year in a row, we are scrounging to find enough marestail at the OARDC Western Ag Station to conduct the research we had planned on this weed.  After years of having plenty of marestail, we have had to look around for off-site fields where there is still a high enough population.  Which, since we are scientists after all, or at least make our best attempts, left us thinking about reasons for the lack of marestail, and our overall maresta

    Issue: 2019-10

  6. What’s Legal to Apply to the LL-GT27 Soybean – The (maybe almost) Final Story

    Author(s): Mark Loux

    Having to issue a retraction to previous C.O.R.N.

    Issue: 2019-05
  7. cereal rye cover crop

    Cover Crop Survey - Quick and Painless

    Author(s): Mark Loux

    OSU weed scientists are in the process of planning cover crop research, and could use your input. Cover crop use has been on the rise in recent years, most commonly for the preservation of soil, reduction in nutrient loss, and suppression of weeds they can provide. Feedback from this survey will allow us to perform trials that are in line with practices common in the state of Ohio and thus generate more impactful results. Thank you!

    Please take our five second survey!

    Issue: 2018-23
  8. Seed heads of Palmer amaranth and waterhemp

    No Pigweed Left Behind - Late-Season Scouting for Palmer Amaranth and Waterhemp

    Author(s): Mark Loux

    If you don’t already have to deal with waterhemp or Palmer amaranth, you don’t want it.  Ask anyone who does.  Neither one of these weeds is easy to manage, and both can cause substantial increases in the cost of herbicide programs, which have to be constantly changed to account for the multiple resistance that will develop over time (not “can”, “will”).  The trend across the country is for them to develop resistance to any new herbicide sites of action that are used in POST treatments.  Preventing new infestations of these weeds should be of high priority for Ohio growers.  When not adequa

    Issue: 2018-23

  9. Reminders about dicamba

    Author(s): Mark Loux

    This is the time of year when we received our first call about dicamba problems in soybeans in 2017.  We can probably expect any problems to become evident soon, based on the timing of postemergence applications and timeline for development of symptoms.  Off-target issues have already developed in states farther west and south, and we would expect at least some to occur here, unless we’re really lucky.

    Issue: 2018-19
  10. Cressleaf Groundsel. Source: S. Noggle, 2017

    Weed of the Week: Cressleaf Groundsel

    Author(s): Sarah Noggle

    Many questions come into the County Extension Office daily.  Many times those include a question about a weed identification.  During the month of June 2018, OSU Extension will be featuring a weed identification of the week.  This week's weed is cressleaf groundsel, Senecio glabellus. 

    Issue: 2018-16

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