Noxious Weeds

2023 Regional Weeds University

OSU Extension invites crop producers, CCAs, and agribusinesses to attend a regional 2023 Ohio Weed University on Wednesday, March 1, from 9:00 a.m. to 4:00 p.m. at the Ramser 4H Activity Center, 700 Perimeter Dr. Mount Vernon, OH.

This program is designed to keep agronomic producers on the cutting edge in weed control for their cropping operations. Topics addressed will include hot topics in weed control, local weed issues, biology, identification of weeds, control strategies, and evaluating herbicides. Hands-on exercises weed identifications will be included.

Featured speakers will include Dr. Aaron Hager, Associate Professor, Department of Crop Sciences, University of Illinois; Dr. Patrick Tranel, Professor, Weed Science, University of Illinois; Dr. Alyssa Essman, visiting Professor and acting State Weed Specialist, The Ohio State University; and, Tony Dobbels, Research Specialist, The Ohio State University. This is an “in-person” event with a of the program being conducted virtually at the above locations.

Dr. Hager contributes to increased crop production through the development and implementation of integrated weed management programs. His research helps to identify and manage herbicide resistance in the most aggressive agronomic weeds. Dr. Tanel’s research and teaching is based on weed science, with an emphasis on the evolution, genetics, molecular biology, and genomics of agronomic weeds. His specialties include herbicide resistance and weedy Amaranthus species. Dr. Essman’s research is setting up a long-term research project looking at the effects of cover crops and herbicide inputs on waterhemp populations and seed bank dynamics. Dobbels manages the herbicide evaluation and field research program in row crop weed control at Ohio State.

The registration fee per person is $40.  Call OSU Extension 740-397-0401 to register.  

Registration deadline is Monday February 27.

Click here to view agenda

Save the Dates – Central Ohio Agronomy School

Due to COVID uncertainties the 2022 Central Ohio Agronomy School has been pushed to March. 

Monday March 7 – 6:30 – 9:00p.m.

Monday March 14 – 6:30 – 9:00p.m.

Monday March 21 – 6:30 – 9:00p.m.

Monday March 28 – 6:30 – 9:00p.m.

The School will be at the new Ramser 4-H Activity Center (on the fairgrounds)

700 Perimeter Dr.  Mount Vernon, OH  43050

More details to come

Poison Hemlock Control

Source: Mark Loux, Curtis Young, OSU Extension

Poison hemlock remains one of the more persistent and prevalent poisonous weeds that we deal with in Ohio.  It’s most typically a biennial plant (sometimes perennial), emerging from seed in year one and developing into a low-growing rosette by late fall.  The rosette overwinters and then resumes growth in the spring of year two.  Stem elongation initiates sooner in spring than many other biennials, and this is followed by continued growth and development into the often very tall plant with substantial overall size.  Flowering and seed production occur in summer.

Failure to control poison hemlock occurs partly because, while it often grows in edges and fencerows around crop fields, no one really pays much attention to it until it does reach this large size when it’s less susceptible to herbicides.  And everyone is busy getting crops planted  in spring anyway so control of hemlock gets low priority.  Stages in the poison hemlock life cycle when it is most susceptible to control with herbicides are:  1) fall, when in the low-growing rosette stage; and 2) early spring before stem elongation occurs.  It’s most easily controlled in fall, but several products can work well in spring.  Herbicide effectiveness ratings for poison hemlock can be found in Table 21 of the current Weed Control Guide for Ohio, Indiana, and Illinois.  Herbicides rated 8 or 9 on poison hemlock include the following:  9 – Crossbow, Remedy Ultra; 8 – Cimarron Max, Curtail, dicamba, glyphosate.  Mixing glyphosate and dicamba can improve control compared with either applied alone.

Several online resources cover poison hemlock more comprehensively than this article does, including this one from the University of Missouri.  Information on toxicity can also be found via an internet search or by contacting OSU Extension if help is needed to resolve a specific concern.

Noxious weeds on your property: what is your responsibility?

Source: Ellen Essman, OSU

Despite the fact that “pumpkin spice” everything is back in stores, it is still summer, and if you’re anything like me, you’re still dealing with weeds. In fact, we have been receiving many questions about noxious weeds lately.  This blog post is meant to be a refresher about what you should do if noxious weeds sprout up on your property.

What are noxious weeds?

The Ohio Department of Agriculture (ODA) is in charge of designating “prohibited noxious weeds.”  The list may change from time to time, but currently, noxious weeds include:

  • Shatter cane (Sorghum bicolor)
  •  Russian thistle (Salsola Kali var. tenuifolia).
  • Johnsongrass (Sorghum halepense ).
  •  Wild parsnip (Pastinaca sativa).
  • Grapevines (Vitis spp.), when growing in groups of one hundred or more and not pruned, sprayed, cultivated, or otherwise maintained for two consecutive years.
  • Canada thistle (Cirsium arvense ).
  • Poison hemlock (Conium maculatum).
  •  Cressleaf groundsel (Senecio glabellus).
  • Musk thistle (Carduus nutans).
  • Purple loosestrife (Lythrum salicaria).
  • Mile-A-Minute Weed (Polygonum perfoliatum).
  • Giant Hogweed (Heracleum mantegazzianum).
  • Apple of Peru (Nicandra physalodes).
  • Marestail (Conyza canadensis)
  • Kochia (Bassia scoparia).
  • Palmer amaranth (Amaranthus palmeri).
  • Kudzu (Pueraria montana var. lobata).
  • Japanese knotweed (Polygonum cuspidatum).
  • Yellow Groove Bamboo (Phyllostachys aureasculata), when the plant has spread from its original premise of planting and is not being maintained.
  • Field bindweed (Convolvulus arvensis).
  • Heart-podded hoary cress (Lepidium draba sub. draba).
  • Hairy whitetop or ballcress Lepidium appelianum).
  • Perennial sowthistle (Sonchus arvensis).
  • Russian knapweed (Acroptilon repens).
  • Leafy spurge (Euphorbia esula).
  • Hedge bindweed (Calystegia sepium).
  • Serrated tussock (Nassella trichotoma).
  • Columbus grass (Sorghum x almum).
  • Musk thistle (Carduus nutans).
  • Forage Kochia (Bassia prostrata).
  • Water Hemp (Amaranthus tuberculatus).

The list of noxious weeds can be found in the Ohio Administrative Code section 901:5-37-01. In addition to this list, Ohio State has a guidebook that will help you identify noxious weeds in Ohio, which is available here.  It may be helpful to familiarize yourself with the weeds in the book, so you can be on the lookout for noxious weeds on your property.

When am I responsible for noxious weeds?

The Ohio Revised Code addresses noxious weeds in different parts of the code. When it comes to noxious weeds on the property of private individuals, there are two scenarios that may apply: noxious weeds on private property, and noxious weeds in line fence rows.

Noxious weeds on your property

If your property is located outside of a municipality, a neighbor or another member of the public can inform the township trustees in writing that there are noxious weeds on your property. If this happens, the township trustees must then turn around and notify you about the existence of noxious weeds. After receiving a letter from the trustees, you must either destroy the weeds or show the township trustees why there is no need for doing so. If you do not take one of these actions within five days of the trustees’ notice, the township trustees must cause the weeds to be cut or destroyed, and the county auditor will assess the costs for destroying the weeds against your real property taxes.  If your land is in a municipality, similar laws apply, but you would be dealing with the legislative authority, like the city council, instead of township trustees.

What if you rent out your land out to be farmed or otherwise?  Are you responsible for noxious weeds on your property in that situation?  The answer is probably.  The law states that the board of township trustees “shall notify the owner, lessee, agent, or tenant having charge of the land” that they have received information about noxious weeds on the property (emphasis added).  Furthermore, the law says that the “person notified” shall cut or destroy the weeds (or have them cut or destroyed).  In all likelihood, if you own the land, you are going to be the person who is notified by the trustees about the presence of weeds.  If you rent out your property to be farmed or otherwise, you may want to include who is responsible for noxious weeds in the language of the lease.

Noxious weeds in the fence row

The “line fence law” or “partition fence law” in Ohio requires landowners in unincorporated areas to cut all noxious weeds, brush, briers and thistles within four feet and in the corners of a line fence. A line fence (or partition fence) is a fence that is on the boundary line between two properties. If you fail to keep your side of the fence row clear of noxious weeds and other vegetation, Ohio law provides a route for adjacent landowners concerned about the weeds. First, an adjacent landowner must request that you clear the fence row of weeds and must allow you ten days to do so. If the weeds still remain after ten days, the complaining landowner may notify the township trustees of the situation. Then, the township trustees must view the property and determine whether there is sufficient reason to remove weeds and vegetation from the fence row. If they determine that the weeds should be removed, the township trustees may hire someone to clear the fence row.  Once again, if this occurs, the county auditor will assess the costs of destruction on your property taxes.

Being aware of noxious weeds is key. 

As a landowner, it is really important for you to keep an eye out for noxious weeds on your property.  If you keep on top of the weeds, cutting them or otherwise destroying them as they grow, it will certainly make your life a lot easier. You will avoid awkward conversations with neighbors, letters from your township trustees, and extra charges on your property taxes. Additionally, you will help to prevent the harm that noxious weeds may cause to crops, livestock, and ecosystems in general.

To learn more about Ohio’s noxious weed laws, you can access our law bulletin on the subject here.  While the bulletin addresses the responsibilities of landowners, it also goes beyond the scope of this blog post, addressing weeds on roadways, railroads, and public lands, as well as how to respond if your neighbor has noxious weeds on their property.  Additionally, the bulletin has a helpful section of “frequently asked questions” regarding noxious weeds.

Noxious weeds on your property: what is your responsibility?

Written by Ellen Essman

Despite the fact that “pumpkin spice” everything is back in stores, it is still summer, and if you’re anything like me, you’re still dealing with weeds. In fact, we have been receiving many questions about noxious weeds lately.  This blog post is meant to be a refresher about what you should do if noxious weeds sprout up on your property.

Continue reading →

Late-Season Waterhemp – The Goal is Stopping Seed

Source: Mark Loux, OSU

I am seeing an increase in both waterhemp and palmer amaranth in Knox County this year.  These can be devestating weeds and if not properly managed, can increase your herbicide costs dramatically.  Make sure you are scouting for these weeds now!

In our windshield scouting of soybeans this year we have seen a lot of weedfree fields.  This makes sense given the shift toward Xtend, LibertyLink, LLGT27, and Enlist soybeans over the past several years, which provides us with effective POST options for our major weed problems – common and giant ragweed, marestail, and waterhemp (now if we could just get rid of the baggage some of these traits carry).  We are however getting many reports of late-season waterhemp as it grows through the soybeans and becomes evident.  This also makes sense given that statewide we are in the midst of an overall increase in waterhemp, and continue to move up the curve in terms of number of fields infested and the size of the infestations.  Prevention and management of waterhemp and Palmer amaranth has been one of the primary goals of our state and county educational programs for half a decade or more.  And one of the most important points about waterhemp and Palmer that we try to get across is their capacity for prodigious seed production – 500,000 to upwards of a million seeds per plant – and what this means for their ability to rapidly ramp up populations, infest equipment, etc.

The bottom line here is that it’s essential to scout fields this time of the season and kill or remove plants that could produce seed.  Allowing even a few plants to produce seed means an increased population for the next year or two at least.  Running harvest equipment through plants loaded with seed is a primary mechanism of spread from field to field.  Plants can survive into late season because they emerged after herbicide treatments, or survived an improperly timed and less than effective POST treatment.  These plants should produce less seed than plants allowed to grow full season without interruption.  It’s also possible given waterhemp’s propensity to become resistant to any herbicide used against it, that the survivors are resistant to whatever POST herbicide was used.  Resistance to glyphosate, ALS, and PPO inhibitors is widespread in Ohio, and we expect the development of resistance to dicamba, 2,4-D, and glufosinate will occur given their intensity of use (which is why the current period of clean fields makes us nervous).  The only way to ensure that resistance does not develop is to follow herbicide programs with later season scouting and removal of plants to prevent seed.

The most effective way to prevent seed is to cut off waterhemp or Palmer plants just below soil line, remove plants from the field, and burn or compost or bury deep enough.  Plants left in the field can reroot at multiple nodes and regrow.  Another option to at least reduce seed production – use a weedeater to cut the tops of plants off.  Once plants develop mature seed (hard brown or black), most effective strategy may be to cut off and bag up seedheads and remove from field.  The value of herbicides this late in the season is questionable.  PPO herbicides are the only legal option at this point, with following restrictions (DBH = days before harvest; from Table 18 of Weed Control Guide):  Cobra/Phoenix – 45 DBH; fomesafen – 45 DBH; Ultra Blazer – 45 DBH.  Carryover and injury to corn from late-season applications of fomesafen is possible.  None of these herbicides are likely to kill large waterhemp plants although they may reduce suppress smaller plants enough to reduce seed.  Keep in mind that PPO inhibitors would be completely ineffective in waterhemp populations that are resistant to PPO inhibitors.

We suggest taking some time from now into September to scout fields for waterhemp and Palmer amaranth with the goal of preventing seed.  If you are lucky enough to have avoided waterhemp, use scouting to maintain this status and prevent new infestations.  If you are currently managing waterhemp infestations, consider late-season removal of plants as an important component of that management plan, and critical to maintaining POST herbicide utility.  Scouting should include local roadsides and waterways, and areas of fields subject to flooding or near migratory bird or deer paths.  Since combines are an effective dispersal mechanism, check the part of fields first harvested where combines are started up.  If you need to harvest fields with waterhemp or Palmer amaranth, harvest these last followed by thorough cleaning of combines, grain carts, semis, etc.  These efforts can go a long way toward avoiding future headaches and increased production costs.

Continue reading →

Ohio Noxious Weed Law

Its that time of year when some of our ugly weeds begin to make their presence known by rising above crop canopies, appearing along the side of the road, etc.  I typically receive many questions about noxious weed identification, control, legal issues, and more.  Below is the first page of the OSU Law Bulletin on Noxious weeds.  Click here to download the complete bulletin.