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.

Burndown Herbicides for No-till Wheat

Source:  Mark Loux, OSU

Herbicide options for burndown of existing weeds prior to planting of no-till wheat include glyphosate, Gramoxone, Sharpen, and dicamba.  Among these, the combination of glyphosate and Sharpen probably provides the best combination of efficacy on marestail, flexibility in application timing and residual control.  Dicamba labels have the following restriction on preplant applications – “allow 10 days between application and planting for each 0.25 lb ai/A used”.  A rate of 0.5 lb ai/A would therefore need to be applied at least 20 days before planting.  We do not know of any 2,4-D product labels that support the use of 2,4-D prior to or at the time wheat planting.  There is some risk of stand reduction and injury to wheat from applications of 2,4-D too close to the time of planting.  Liberty and other glufosinate products are also not labeled for use as a burndown treatment for wheat.  Sharpen should provide limited residual control of winter annuals that emerge after herbicide application, and the rate can be increased from 1 to 2 oz/A to improve the length of residual.  Gramoxone should also effectively control small seedlings of marestail and other winter annuals.  Be sure to use the appropriate adjuvants with any of these, and increase spray volume to 15 to 20 gpa to ensure adequate coverage with Sharpen or Gramoxone.

There are several effective postemergence herbicide treatments for wheat that can be applied in November to control these weeds, in fields where preplant burndown treatments are not used.  The most effective postemergence treatments include Huskie, Quelex, or mixtures of dicamba with either Peak, tribenuron (Express etc), or a tribenuron/thifensulfuron premix (Harmony Xtra etc).  We discourage application of 2,4-D to emerged wheat in the fall due to the risk of injury and yield reduction.

Herbicide Residue Considerations for Fall Cover Crop Establishment

Source: Alyssa Essman, Mark Loux, OSU

Herbicides with residual that are used in corn and soybeans can affect the establishment of fall-planted cover crops, and should be taken into account when planning cover crop practices and selecting species. Soil characteristics and weather also play a role in the persistence of residual herbicides, which can vary by field and year. More information is needed on rotational intervals for many cover crop species, and this information is often not included on herbicide labels. University weed scientists have studied the effect of residual herbicides on some of the most popular cover crop species in order to provide this information to growers. In general, residual herbicides that control grass weeds can hinder establishment of grass cover crop species. Broadleaf cover crop species are most impacted by group 2 (ALS inhibitors), 5 (PSII inhibitors), 14 (PPO inhibitors), and 27 (HPPD inhibitors) herbicides (Purdue University).

A multi-state study found that the general order of sensitivity of cover crops to herbicide carryover, from greatest to least sensitive, is:

  • Tillage radish > Austrian winter pea > crimson clover = annual ryegrass > winter wheat = winter oats > hairy vetch = cereal rye.

Soybean herbicides that tended to be most injurious were:

  • Fomesafen, pyroxasulfone, imazethapyr, acetochlor, and sulfentrazone.

Corn herbicide treatments that were most injurious to cover crops were:

  • Topramezone, mesotrione, clopyralid, isoxaflutole, pyroxasulfone, and nicosulfuron

(University of Missouri).

Below is a table of commonly used corn and soybean herbicides, the fall cover crops that are safe to plant in rotation, and cover crop species that may be injured following these herbicides (Adapted from Lingenfelter D. and Curran W., Penn State University).

 

 

Cover crops provide a multitude of benefits and their use is becoming an increasingly popular practice in Ohio. Including cover crops in rotation with agronomic crops to realize these benefits costs time and money. It is important to evaluate the potential risk of herbicide residue on the establishment of cover crops in order to ensure success. Residual herbicides applied at the time of planting typically interfere with cover crop establishment less than those applied POST. Weather can affect the persistence of herbicides also, especially rainfall in summer.  The risk of residual herbicides affecting cover establishment will be higher in areas that have been dry since herbicide application.  Risk will be lower where the herbicide application was followed by some wet weather to get herbicide degradation started, compared with an application during prolonged dry weather.  One of the least problematic cover crop species is cereal rye, which can be successfully established following a late corn or soybean harvest, and is tolerant to a most of the most commonly used corn and soybean herbicides. Weed control should continue to be the priority in selecting herbicides, and cover crop species selection should be based on potential injury and goals for the use of cover crops.  The introductory section of the “Weed Control Guide for Ohio, Indiana, and Illinois” has some of the same information presented here, and OSU weed scientists also summarize this in a video: https://www.youtube.com/watch?v=ylr0zGnXMfs

The following resources contain information on residual herbicides and cove crops also:

https://extension.psu.edu/corn-herbicides-and-rotation-to-cover-crops https://extension.psu.edu/soybean-herbicides-and-rotation-to-cover-crops

https://ipm.missouri.edu/IPCM/2020/3/coverCropTermination-KB/

https://ag.purdue.edu/btny/weedscience/Documents/covercropcarryover.pdf

Preharvest Herbicide Treatments

Source:  Mark Loux, OSU

Information on preharvest herbicide treatments for field corn and soybeans can be found in the “Weed Control Guide for Ohio, Indiana, and Illinois”, at the end of these crop sections (pages 72 and 143 of the 2020 edition).  Products listed for corn include Aim, glyphosate, and paraquat, and for soybeans include Aim, paraquat, glyphosate, and Sharpen.  Some dicamba products are also approved for preharvest use in soybeans, and some 2,4-D products are approved for use in corn, and these are not listed in the guide.  The basic information for these follows:

Dicamba – soybeans:  Apply 8 – 32 oz/A (4 lb/gal products) as a broadcast or spot treatment after soybean pods have reached mature brown color and at least 75% leaf drop has occurred; soybeans may be harvested 14 days or more after a pre-harvest application; do not use preharvest-treated soybean for seed unless a germination test is performed on the seed with an acceptable result of 95% germination or better; do not feed soybean fodder or hay following a preharvest application of this product.

2,4-D – corn:  Labels vary with regard to types of corn that can be treated (some indicate no sweet corn) and based on whether crop is being grown for seed.  Apply after the hard dough (or dent) stage when silks have turned brown.  Weed seed production can be suppressed if applied prior to the flowering stage.  Allow 14 days between application and grain harvest.  Do not forage or feed corn fodder for 7 days after application.

Preharvest herbicide treatments are primarily intended to suppress/kill and dessicate weeds that can make harvest more difficult.  Products with contact activity will cause faster dessication and leaf drop of weeds, but may be less effective at killing weeds compared with systemic products.  Effective dessication with contact herbicides may still require a wait of a week or more following application, and this can can vary by weed.  The maximum paraquat rate is well below the rate required to actually kill large weeds, but it is still probably most effective for dessication of morninglory.  Glyphosate is not likely to be effective on marestail and waterhemp, and many giant ragweed populations, whereas dicamba or 2,4-D may with enough time between application and harvest.  The first frost will usually provide results similar to herbicides, so in a situation where crop maturity is delayed or the infested field can be harvested later in fall, consider whether a herbicide treatment is actually needed.  Preharvest treatments can also be effective for control of warm season perennials, and the systemic herbicides will be most effective where this is the goal.  Keep in mind also that for weeds with fruits that can contaminate harvest, such as black nightshade, the preharvest treatment can dessicate the foliage but will not affect the fruits, except that dessication of weeds may result in fruits closer to the soil.

Preharvest treatments are not intended to be used to speed up crop maturity, and largely do not accomplish this.  The restrictions on preharvest treatments that specify how mature the crop must be at time of application are designed to minimize any effect of herbicides on crop maturation.  Applying earlier than specified could interfere with that process.  The residue tolerances for this use are also based on a certain application timing, and failure to follow label guidelines could result in illegal herbicide residues in grain.  For crops being grown for seed, and for sweet corn and popcorn, be sure to check with the seed company/processor for approval prior to using any preharvest treatments.

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.

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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.

Changes in status of dicamba product labels for Xtend soybeans – a recap

DSource: Dr. Mark Loux, OSU

 

Ohio Department of Agriculture: Dicamba use in Ohio ends June 30, 2020

 

On June 3, the US 9th Circuit Court of Appeals issued a decision in a case concerning the use of dicamba on Xtend soybeans.  This decision voided the labels for XtendiMax, Engenia, and FeXapan that allows use on Xtend soybeans.  Tavium was not included in this decision, because it was not approved for use when the case was initially filed.  Several excellent articles covering this decision can be found here on the OSU Ag Law blog (https://farmoffice.osu.edu/blog).  EPA stated on June 8, providing further guidance about what this decision means for the use of dicamba for the rest of this season.  The gist of this decision was the following:

“EPA’s order addresses sale, distribution, and use of existing stocks of the three affected dicamba products – XtendiMax with vapor grip technology, Engenia, and FeXapan.

  1. Distribution or sale by any person is generally prohibited except for ensuring proper disposal or return to the registrant.
  2. Growers and commercial applicators may use existing stocks that were in their possession on June 3, 2020, the effective date of the Court decision. Such use must be consistent with the product’s previously-approved label, and may not continue after July 31, 2020.”

ODA subsequently issued a statement regarding the registration and use of these products in Ohio, stating that any application must happen before July 1, 2020.  Partial text from this statement:

“The registration of these products (XtendiMax, FeXapan, and Engenia) in Ohio expires on June 30, 2020. After careful evaluation of the court’s ruling, US EPA’s Final Cancellation Order, and the Ohio Revised Code and Administrative Code, as of July 1, 2020, these products will no longer be registered or available for use in Ohio unless otherwise ordered by the courts.

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Distribution of Waterhemp and Palmer Amaranth in Ohio

Source: Dr. 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 remediated.  The number of counties where an infestation(s) is being managed is still low, and within those counties, the outbreak occurs in only a few fields still.  Waterhemp is much more widespread in Ohio and is spreading rapidly within the state from existing infestations to new areas via equipment, water, animals, etc.  We do not have Ag Educators in all counties, and even where we do, infestations can occur without us knowing about them.  Feel free to contact us with new information to update the maps.

Among the weed photos sent to the Agronomy Team members for identification, a fair number lately has been for the purposes of “pigweed” identification.  “Pigweed” as used here can refer to waterhemp, Palmer amaranth, spiny amaranth, Powell amaranth, and redroot/smooth pigweed (these two are mostly the same for ID/control purposes).  It’s almost impossible to tell these apart when they are very small, but this gets easier by the time they are 4 inches tall.  Waterhemp and Smooth/redroot pigweed are still the most common.  Waterhemp is smooth all over with a somewhat elongated leaf with smooth edges, and leaves sometimes can be a darker and glossier green than pigweed.  Smooth/redroot pigweed will have a hairy/rough stem (more defined as it gets larger), with relatively nonglossy leaves that are widest in the middle with “rougher” edges.  Various resources are available to help with identification, including our pigweed ID fact sheet and Youtube video.  Identification of pigweeds is not necessarily straight forward, so feel free to contact your local extension educator or OSU weed scientists (loux.1@osu.edu or ackley.19@osu.edu) for help with identification.