Herbicide resistance: What it looks like in Kansas fields—and what to do next

By Lonnie Mengarelli Ag and Natural Resources Agent – Southwind District

Herbicide resistance is one of the most serious and persistent challenges facing Kansas agriculture and crop production worldwide. Since the first documented case of resistance—wild carrot surviving 2,4-D in 1957—the problem has expanded dramatically. Today, 273 weed species worldwide have evolved resistance to 21 different herbicide modes of action, including many species found right here in Kansas.

When weed control fails, it is critical to determine why. If herbicide resistance is the cause, management programs must be adjusted quickly and decisively. Resistance develops through repeated use of herbicides with the same or similar mode of action at the same site over several years. This repeated selection pressure favors survival of resistant individuals within what was once a susceptible population. Timely diagnosis, regular field scouting, and early detection are essential—not only to reduce yield losses but also to slow the spread of resistance across fields and regions. According to the Weed Science Society of America and Take Action on Weeds, there are three broad field indicators that may signal herbicide resistance.

Species-specific survival occurs when a particular weed survives an herbicide application while nearby plants of the same species are controlled.
Spreading patches appear as clusters of surviving weeds that often expand in following seasons through seed movement by tillage, harvest equipment, or wind.
Mixed injury responses happen when a single weed species shows a range of reactions—some plants dead, others injured, and some completely healthy. This uneven response suggests genetic diversity that can drive further resistance evolution.

These warning signs should raise concern, but it is important to remember that not all herbicide failures are due to resistance. In fact, roughly nine out of ten failures are caused by other factors such as unfavorable weather, incorrect application rates, poor spray coverage, improper timing, large weed size, soil moisture conditions, skips, or equipment problems. Producers typically rely on pre-emergence (PRE), post-emergence (POST), or residual herbicides—often in combination—for broad-spectrum weed control. Knowing how these products should perform is key to identifying potential resistance. POST herbicides normally produce visible injury symptoms such as yellowing, burning, stunting, drooping, or plant death. Residual herbicides, by contrast, should suppress new weed flushes for weeks after application. When weeds continue to emerge or survive despite proper application and favorable conditions, resistance should be suspected and investigated. Field observations provide valuable clues. For example, kochia surviving ALS inhibitors without any stunting, waterhemp emerging weeks after a residual Group 15 herbicide under moist conditions, or horseweed showing no injury following a glyphosate application are all documented red flags.

Field patterns can also hint at the type of resistance involved. Target site resistance often produces uniform, healthy survivors with little or no visible injury. Non-target site resistance tends to show patchy survival and partial injury and is generally more difficult to manage because it may confer resistance across multiple herbicide groups. While laboratory confirmation is needed for certainty, these field-level observations help guide immediate management decisions. If herbicide resistance is suspected, quick action is essential. Post-spray scouting should occur soon after application to assess weed responses. Survivors should be compared across species and field areas. When possible, re-sprays should include multiple effective herbicide modes of action. However, if weeds are too large, a second application may fail, and mechanical control such as cultivation or hand removal may be necessary. Scouting should continue through harvest to identify escapes and inform future crop and herbicide rotations. Producers are encouraged to contact their local extension agent, input supplier, commercial applicator, or weed science specialist if resistance is suspected.

Herbicide resistance continues to threaten effective weed control in Kansas and beyond. While herbicide failure is a major warning sign, other agronomic and environmental causes must be ruled out first. Understanding herbicide modes of action and recognizing when weeds do not respond as expected are critical steps in early detection. Watch closely for dead plants next to live ones, increasing weed populations that were once controlled, and patches or trails of survivors after application. Early detection and rapid response remain the most powerful tools to prevent the spread of herbicide resistance and protect long-term crop productivity.

 Lonnie Mengarelli is a K-State Research and Extension Agriculture agent assigned to Southwind District. He may be reached at [email protected] or 620-223-3720

References

Switzer, C. M. 1957. The existence of 2,4-D–resistant strains of wild carrot. Proc. Northeast. Weed Control Conference. 11:315-318.

Weed Science Society of America (WSSA), & Take Action on Weeds. (2015). Field identification and control of suspected herbicide-resistant weeds. United Soybean Board. Retrieved from https://iwilltakeaction.com/uploads/files/Field-Identification-of-Suspected-Herbicide-Resistant-Weeds.pdf

Yasir Parrey, Assistant Scientist, Weed Extension Lab
[email protected]

Sarah Lancaster, Extension Weed Management Specialist
[email protected]

Patrick Geier, Weed Scientist, Garden City
[email protected]

Learn More about Radon Action Month

Did you know that one in four homes in Kansas has elevated radon levels? January is Radon Action Month, making it the perfect time to learn more about this dangerous gas. Radon is the leading cause of lung cancer among nonsmokers—and you can’t see, smell, or taste it—making it impossible to detect without testing. It naturally seeps up from the soil and can accumulate in your home without you even knowing.

Take action this winter to protect your home and loved ones. Radon test kits are available for just $9.00 at your local extension office in Iola, Erie, Fort Scott, or Yates Center.

Learn more by joining a free Radon 101 Webinar (30 minutes):
Jan 6 – Noon
Jan 13 – 2 PM
Feb 3 – 6 PM
Register here: https://shorturl.at/B1jCa

For more information, call Tara at 620-244-3826.

Walk with Ease Begins January 26^th

Need a free, safe, and warm physical activity option?  A six-week Arthritis Foundation Walk with Ease Program starts January 26^th!  The class will meet on Mondays and Wednesdays from 10:00 to 11:00 a.m. at the Bronson Community Building, located at 509 Clay Street. Call 620-244-3826 to enroll.

 Walk with Ease Benefits to You:

• Walk safely and comfortably
• Improve flexibility, strength, and stamina
• Reduce pain and improve health
• Motivate yourself with others!

This free walking program includes health education, stretching exercises, strengthening exercises, and motivational strategies. The program consists of a guidebook and a walking schedule to get you safely moving toward better health.

Walk with Ease is made available by a partnership between K-State Extension and the Southeast Kansas Area Agency on Aging.

As we close out 2025 and welcome a new year, it is a perfect time to reflect on the past and look ahead to new goals, fresh opportunities, and continued growth. K-State Extension- Southwind District remains committed to serving our communities through practical, research-based education and support for residents of all ages. As 2026 begins, we are excited to highlight the services available to help individuals, families, farms, and communities start the year strong.

Southwind’s 4-H Youth Development, led by Extension Agents Jennifer Terrell and Kendal Henson, continues to be a cornerstone of Extension programming. Youth have opportunities to participate in local 4-H clubs, camps, project-based learning, leadership activities, and competitive events that build confidence and real-world skills. Extension also offers school enrichment programs and career exploration experiences designed to prepare young people for future success while remaining engaged in their communities.

Through Family and Consumer Sciences, Extension Agents Tara Solomon Smith and Sandy Haggard provide services that support healthy families and strong households. Programs include nutrition education, healthy cooking classes, food preservation workshops, and food safety education. Extension also offers Senior Insurance Counseling, aging well programs, and overall wellness education, helping families set positive habits and goals as the new year begins.

The Southwind District proudly supports local producers through Agriculture and Natural Resources programming offered by Extension Agents Hunter Nickell and Lonnie Mengarelli. Services include research-based information on crop and livestock production, pasture and forage management, soil health, pest management, pond management, and conservation practices. Producers can also receive assistance with farm management decisions, recordkeeping, and navigating changes in agricultural technology and markets.

Homeowners and gardeners can work with Horticulture Extension Agent Krista Harding for assistance with insect identification, plant and weed identification, lawn and garden troubleshooting, tree and shrub care, and general gardening questions. Research-based recommendations help residents plan and maintain successful gardens and landscapes throughout the year.

Community Vitality programming, led by Extension Agent Amanda Clasen, helps strengthen local economies and support thriving communities. Services include entrepreneurship education, youth and adult business programs, community planning support, facilitation for local groups, and financial literacy education. By working alongside community members, Extension helps towns identify opportunities, address challenges, and plan for a sustainable future.

One of the greatest strengths of K-State Extension is its local presence. Extension services are accessible, affordable, and tailored to the unique needs of our communities. Whether you are setting personal goals, managing a farm or business, raising a family, or serving your community, Extension is here to help you move forward in the new year.

As we step into 2026, K-State Extension Southwind District looks forward to continuing to serve as a trusted resource and partner. We wish everyone a safe, healthy, and prosperous New Year. To learn more about upcoming programs and services, contact your local Extension office or visit southwind.k-state.edu.

Radon: The Silent Threat Beneath Your Home

 Radon is a gas that comes from the ground. You can’t see it, smell it, or taste it—but it can make you very sick. Breathing radon for a long time can cause lung cancer. In fact, radon is the second leading cause of lung cancer in the U.S. and the number one cause for people who don’t smoke.

Why should you care?
In Kansas, approximately one out of every four homes has excessive radon levels. Each year, about 200 people in Kansas get lung cancer from radon. The only way to know if your home is safe is to test it.

 Testing is easy and cheap.
You can buy a radon test kit for $9 at K-State Extension offices in Iola, Erie, Fort Scott, and Yates Center. Put the kit on the lowest level of your home where people spend time, leave it for a few days, then mail it in. If your test score is 4.0 or higher, your home needs attention.

 What if your home has high radon?
Don’t worry—radon can be fixed. A special system can pull radon out from under your house and send it outside. Most systems cost between $800 and $2,500, and they typically work within one day. After fixing, test again to ensure your home remains safe.

Want to learn more? Join a free 30-minute Radon 101 Webinar:

• Jan 6 – Noon
• Jan 13 – 2 PM
• Feb 3 – 6 PM

Register here: https://shorturl.at/B1jCa

Visit www.kansasradonprogram.org or call 620-244-3826. Don’t wait—test today to protect your family.

Low-Cost Tree and Shrub Seedlings Now Available

The Kansas Forest Service is once again offering low-cost conservation tree and shrub seedlings for purchase. These plants are ideal for a variety of conservation uses, including home or livestock windbreaks, living snow fences, Christmas tree plantations, firewood lots, wildlife habitat, property line markers, noise barriers, and screening undesirable views.

Seedlings are 1–2 years old and range from 12–18 inches tall, depending on species. Most are bare-root, though some—such as ponderosa pine and southwestern white pine—are available as container-grown seedlings. Deciduous options include bald cypress, black walnut, bur oak, cottonwood, hackberry, redbud, and sycamore. Shrub selections include American plum, chokecherry, lilac, and sandhill plum. (This is not a complete list, and not all species are recommended for every area.)

The Kansas Forest Service also offers themed “bundles.”
The Quail Bundle includes a mix of shrubs—American plum, fragrant sumac, golden currant, and chokecherry—chosen to attract quail and improve upland bird habitat in eastern Kansas. It was developed in cooperation with Quail Forever.

The Pollinator Bundle is designed to support a diverse range of pollinating insects, including native bees, honeybees, butterflies, and moths. It contains seven species of shrubs and small trees: American plum, chokecherry, golden currant, false indigo, elderberry, buttonbush, and eastern redbud.

If you’re unsure about what to order, please contact me at the Extension office, and I’ll be happy to help. Orders are accepted January 2 through April 30, with shipments beginning in March. Ordering early is recommended to ensure availability. To place an order, visit kansasforests.org.

Krista Harding is a K-State Research and Extension Horticulture agent in the Southwind District. She can be reached at [email protected] or 620-244-3826.

K-State Research and Extension is an equal opportunity provider and employer.

K-State to Host Calving School in Southeast KS

Program focuses on calving management and handling difficult births.

Kansas State University’s Department of Animal Sciences and Industry and K-State Extension’s Southwind District, Wildcat District, and Cherokee County will host a Calving Management School in Erie as part of a statewide educational effort preparing producers for the upcoming calving season.

The event will be held on Wednesday, Jan. 7, at the Neosho Valley Event Center, 321 N. Wood, Erie, Kansas. Doors will open at 5:30 p.m., and the meal and program will begin at 6:00 p.m. Producers are asked to register online at: https://bit.ly/SEKCalvingSchool2026 or call 620-244-3826. Thanks to the generous sponsorships from the Community Foundation of Southeast Kansas, Cleaver Farm & Home, Merck Animal Health, and Zoetis, producers can attend the program at no charge.

The program will cover overall calving management, including the stages of normal labor and practical tips for managing difficult calving situations. A.J. Tarpoff, K-State Extension beef veterinarian, said the goal of the program is to increase producer knowledge and hands-on skills to support more successful births when assistance is needed.

“We want producers to leave better prepared for calving season,” Tarpoff said. “We will discuss timelines on when to examine cows for problems, when to call your veterinarian if something isn’t progressing normally, and how to provide proper calf care during the first hours of life. It’s an excellent program for all experience levels.”

Dr. Tarpoff will also demonstrate the proper use of calving equipment using a life-size cow and calf model. Local extension agents will also cover Body Condition Scoring and a Calving Tool-Kit.

For more information, please contact Hunter Nickell, Livestock Production Agent, (620) 244-3826, [email protected].

Which Potato Should I Buy?

Those of us in Kansas are used to eating meat and potatoes almost everyday. Who doesn’t enjoy mashed potatoes with chicken noodles on a cold gray day in the winter, or eating potato casseroles? There are many varieties of potatoes in the grocery store, so how do you choose which potato to buy for which situation? While many shoppers choose potatoes based on personal preference, there are some guidelines to help choose the right potato for the right recipe.

Potato preparation is based on two quality characteristics, starch and moisture content. These two components can determine the best way to cook them.

High starch/low moisture – The russet potato fits in this category. The high solids content yields a dry, fluffy, mealy texture well suited for baking, mashing, frying, or pureeing. They also make good French fries.

Low to medium starch/high to medium moisture – Red and yellow potatoes fit in this category. They have a waxy texture which makes them good for boiling, steaming, braising, stewing, in salads, or any other recipe where potatoes need to remain intact. They don’t absorb much water during cooking, so they have a smooth, creamy texture.

Here are some common varieties and their uses:

Russet – baking, mashing, frying, roasting

Whites – boiling, steaming, mashing, baking, roasting and in casseroles (scalloped and au gratin), soups and salads.

Reds – boiling, roasting, steaming and in casseroles (scalloped and au gratin), soups and salads.

Yellows – baking, boiling, mashing or roasting.

Blue/Purple – bake or mash, French fry, steam, or boil.

Fingerlings – steam, bake, or boil; also good in salads.

Potatoes can provide essential nutrients such as potassium, Vitamin C, and fiber. They are suitable for those with digestive issues, and by themselves, they are fat-free, gluten-free, plant-based, and they are often affordable.

Enjoy your family gatherings and keep safe food handling tips in mind for the health of your family members. For further information on nutrition programming such as Dining with Diabetes or Planning Family Meals, please contact Sandy Haggard, Nutrition, Food Safety, and Health Agent, Southwind District, [email protected] or 620.365.2242.

50 Years of Herbicide Resistance in Kansas: How We Got Here and What’s Next

By Lonnie Mengarelli Ag and Natural Resources Agent – Southwind District

This year marks 50 years since Kansas documented its first herbicide-resistant weed. That 1976 discovery—triazine-resistant kochia along railroad rights-of-way—seemed like an isolated case at the time. Today, herbicide resistance is one of the most serious challenges facing Kansas farmers. As we recognize this anniversary, it’s worth looking back at how resistance evolved, where we stand now, and what it will take to manage it moving forward.

Herbicide resistance is the ability of a weed population to survive an herbicide dose that would normally kill it. This is different from herbicide tolerance, which is a weed’s natural, built-in ability to withstand a certain herbicide.

Resistance develops when herbicide use selects for rare genetic traits that allow certain plants to survive and reproduce. Over time, those traits become more common in the field.

Kochia set the stage for herbicide resistance problems in Kansas. After atrazine-resistant kochia was identified in 1976, resistance spread rapidly thanks to the plant’s tumbling growth habit and widespread use of triazine herbicides in crop fields.

Another milestone came in 1987, when kochia populations resistant to ALS-inhibiting herbicides (Group 2) were confirmed. Since then, kochia has added resistance to dicamba and fluroxypyr (Group 4) and glyphosate (Group 9), making it one of the most challenging weeds in the High Plains.

Palmer amaranth and waterhemp—two aggressive pigweed species—have become the state’s most notorious resistant weeds.

Palmer amaranth resistance to Group 2 herbicides was identified in 1993, and the species has since developed resistance to at least six herbicide groups. Palmer amaranth is the only Kansas weed with documented resistance to HPPD herbicides (Group 27), and resistance to Group 15 herbicides has been confirmed just south of the Kansas border. More recently, dicamba-resistant Palmer amaranth was identified for the first time.

Waterhemp has a similar story. By 1995, Kansas populations were already resistant to both Group 2 and Group 5 herbicides, and glyphosate resistance followed in 2006. Both Palmer amaranth and waterhemp are dioecious, meaning they cross-pollinate readily—and that genetic shuffling speeds up the spread of resistance traits.

As of 2025, 16 weed species in Kansas have confirmed herbicide resistance. Thirteen of these are broadleaf weeds; three are grasses. Many are winter annuals that emerge in the fall and cause problems the following spring.

The largest number of resistant species—13—is associated with Group 2 herbicides. Glyphosate resistance (Group 9) ranks second, with six resistant species identified.

The busiest years for new resistance confirmations were 2013 and 2021, each with six new cases. Only two new cases have been added since 2021, but researchers caution that this does not signal a slowdown—only that resistance often goes undetected for several years before being confirmed.

Herbicide resistance will continue to evolve. It is a natural biological process, but it is accelerated when the same herbicide modes of action are used repeatedly. Kansas farmers have faced this steady march for five decades, and the path forward will require more than relying on new chemistry.

The most effective long-term strategy is integrated weed management—diversifying herbicide programs, incorporating cultural and mechanical practices, and reducing seed production by surviving weeds. More details on these strategies will be covered in a follow-up article.

Lonnie Mengarelli is a K-State Research and Extension Agriculture agent assigned to Southwind District. He may be reached at [email protected] or 620-223-3720

 K-State Research and Extension is an equal opportunity provider and employer.

Reference:
Heap, I. 2025. International Herbicide-Resistant Weed Database.

For additional information, see the 2025 Chemical Weed Control for Field Crops, Pastures, and Noncropland or contact your local K-State Research and Extension office.

Patrick Geier, Weed Scientist, Garden City
Yasir Parrey, Assistant Scientist, Weed Extension Lab
Sarah Lancaster, Extension Weed Management Specialist

Libraries with Heart Initiative Expands Access to Blood Pressure Monitoring Across Southeast Kansas

Nearly half of all Americans have high blood pressure, a leading risk factor for heart attack and stroke.  In a collaborative effort to improve community health, five local libraries have launched the Libraries with Heart initiative, a program designed to increase access to blood pressure monitoring and education.

This initiative is made possible through a General Funds Basic Human Needs grant from the Community Foundation of Southeast Kansas, in partnership with K-State Extension – Southwind Extension Education Foundation, the American Heart Association, and participating libraries.

Libraries with Heart empowers individuals to take control of their health by providing tools and resources to monitor and manage blood pressure effectively.

Program Highlights:

• Validated Blood Pressure Monitors for Check Out:  Patrons can borrow monitors through the Library of Things catalog.
• Educational Materials: Staff and community members are equipped with easy-to-understand resources on how to use the monitors, understanding blood pressure, and how to take steps toward better heart health.
• Healthcare Connections: Resources of local healthcare providers for further support and follow-up care.

“This initiative is a great example of how libraries truly serve as hubs for community wellness,” said Tara Solomon-Smith, Healthy Heart Ambassador and Extension Agent with K-State Extension. “By making blood pressure monitoring more accessible, we’re helping individuals take proactive steps toward healthier lives.”

The Libraries with Heart initiative reflects a shared commitment to public health, education, and community empowerment. Each participating library brings its own unique approach, while maintaining core elements that ensure consistency and impact across the region.

For more information about the program or to find a participating library near you, contact Tara Solomon-Smith at [email protected] or 620-244-3826.

Embrace Winter this Season

Do you find yourself ready for bed as soon as supper is over this time of year? You’re not alone—many of us feel that way after the time change. But winter doesn’t have to be something we dread. With a few simple strategies, we can make the most of the season and enjoy it!

Brighten Your Days with Light Therapy

Light therapy can help combat the winter blues by mimicking natural sunlight. Light boxes or lamps produce bright white light that signals your brain, much like daylight does. When choosing a light box, Harvard Health Publishing recommends:

• Look for 10,000 lux exposure. (Lux measures light intensity; a sunny day is about 50,000 lux.)
• Position it correctly. Keep the box in front of you or slightly to the side, about a foot away. Don’t stare directly at the light—read, meditate, or watch TV instead.
• Use it consistently. Aim for about 30 minutes of exposure daily. You can break this into shorter sessions.

Lifestyle Tips for a Positive Winter

Oklahoma State University Extension suggests creating a plan to boost your mood long-term:

• Bundle up and spend 15–30 minutes outdoors for sunlight and exercise.
• Maintain a healthy routine of sleep, movement, and nutritious meals.
• Take medications as prescribed if managing depression.
• Limit alcohol, as it can worsen symptoms.
• Stay connected—make plans and follow through.
• Practice self-care and kindness toward yourself and others.

Find the Bright Side of Winter

Psychologist and author Kari Leibowitz encourages focusing on what you enjoy about winter. Make a list of things you look forward to—like lighting candles. Leibowitz notes that when you light candles with the intention of celebrating the darkness, it can transform your experience and give winter a new meaning.

Wishing you a wonderful season filled with new ways to embrace winter! For more information, please contact Tara Solomon-Smith at [email protected] or 620-244-3826.

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Kansas State University Agricultural Experiment Station and Cooperative Extension Service