How to Get Rid of Johnson Grass in Hay Field (5 Pro Timber Tips)

Have you ever felt that knot of frustration tighten in your stomach as you survey your hay field, seeing those telltale green blades of Johnson grass stubbornly refusing to yield? I know I have. It’s like finding a weed in your favorite garden, only this weed threatens your entire livelihood. For years, I battled this invasive plant, pulling, spraying, and strategizing, learning hard lessons along the way. And believe me, it’s not just about aesthetics; it’s about the quality of your hay, the health of your livestock, and, ultimately, your bottom line.

That’s why I’ve poured my years of experience into this guide, sharing five pro-timber tips – yes, timber tips, because some of the strategies I’ve adapted come straight from the forestry world – to help you reclaim your hay field from the relentless Johnson grass. This isn’t just theory; it’s the practical, hands-on advice I wish I had when I first started. Let’s dive in, and together, we’ll conquer this grassy foe.

Understanding Johnson Grass and Its Impact

Before we jump into eradication methods, let’s understand our adversary. Sorghum halepense, commonly known as Johnson grass, is a perennial grass native to the Mediterranean region. It’s characterized by its tall stature (up to 6 feet), aggressive growth habit, and extensive rhizome system. This rhizome system is key to its survival and makes it incredibly difficult to eliminate.

Why is Johnson grass a problem in hay fields?

• Reduced Hay Quality: Johnson grass is less palatable and nutritious than desirable forage grasses. Its presence lowers the overall quality of your hay, affecting its market value and nutritional benefits for livestock.
• Cyanide Poisoning Risk: Under certain conditions, such as drought or frost, Johnson grass can produce prussic acid (cyanide), which is toxic to livestock. This poses a serious health risk, especially to ruminants like cattle and sheep. Data shows that prussic acid levels above 200 ppm (parts per million) can be lethal to livestock. Research from Purdue University indicates that levels can spike dramatically following a frost, sometimes exceeding 500 ppm.
• Competition for Resources: Johnson grass competes with desirable forage species for sunlight, water, and nutrients, hindering their growth and productivity. This results in lower hay yields and increased costs for fertilization and other inputs.
• Spread and Persistence: Johnson grass spreads rapidly through seeds and rhizomes, quickly infesting new areas. Its deep rhizome system makes it resistant to many control methods, allowing it to persist for years even with repeated treatments.

Technical Data Point: A study by the USDA found that Johnson grass infestations can reduce hay yields by as much as 50% in heavily infested fields. The same study showed that the protein content of hay containing Johnson grass was, on average, 15% lower than hay from fields free of the weed.

Identifying Johnson Grass

Accurate identification is the first step in effective control. Here’s what to look for:

• Tall Stature: Johnson grass typically grows taller than most desirable forage grasses, often reaching heights of 4-6 feet.
• Broad Leaves: The leaves are relatively broad, measuring up to 1 inch wide and 2 feet long. They have a prominent midrib and a slightly rough texture.
• Panicle Seedhead: The seedhead is an open, branching panicle that emerges in late summer. The seeds are small, oval-shaped, and reddish-brown.
• Rhizomes: The most distinctive feature of Johnson grass is its extensive rhizome system. These underground stems are thick, scaly, and white to tan in color. They spread horizontally, forming a dense network that allows the plant to colonize new areas.

Visual Example: Imagine a network of white, fleshy roots spreading aggressively beneath the soil’s surface. These are the rhizomes, the plant’s secret weapon for survival.

Pro Timber Tip #1: Strategic Mowing and Grazing

One of the most effective, yet often overlooked, control methods is strategic mowing and grazing. This approach, inspired by timber stand improvement practices, focuses on weakening the Johnson grass by depleting its energy reserves.

How it works:

• Mowing: Regular mowing, especially during the plant’s active growth phase, prevents it from producing seeds and depletes its energy reserves stored in the rhizomes.
• Grazing: Controlled grazing can also help suppress Johnson grass. Livestock, particularly cattle, will graze on Johnson grass, especially when other forage is limited. However, it’s crucial to manage grazing carefully to avoid overgrazing desirable species and to be aware of the potential for cyanide poisoning.

Technical Details:

• Mowing Height: Mow at a height of 4-6 inches. This allows desirable forage grasses to recover while suppressing Johnson grass growth.
• Mowing Frequency: Mow every 2-3 weeks during the active growing season (spring and summer). Adjust the frequency based on Johnson grass regrowth.
• Grazing Management: Use rotational grazing to prevent overgrazing. Divide your pasture into smaller paddocks and rotate livestock among them, allowing each paddock to recover before being grazed again.

My Experience: I remember one year, I was particularly diligent with my mowing schedule. I mowed my hay field every two weeks, religiously. By the end of the season, the Johnson grass was noticeably weaker, and the desirable grasses were thriving. It was a testament to the power of consistent management.

Data-Backed Insight: Research from the University of Missouri shows that mowing Johnson grass at a height of 4 inches every 3 weeks can reduce its biomass by up to 50% over a single growing season.

Safety Note: Always inspect your hay field for signs of stressed Johnson grass (e.g., wilting, discoloration) after frost or drought. If you suspect cyanide poisoning, remove livestock immediately and consult with a veterinarian.

Pro Timber Tip #2: Targeted Herbicide Application

While I prefer non-chemical methods whenever possible, sometimes herbicides are necessary to control severe Johnson grass infestations. The key is to use them strategically and responsibly.

Herbicide Selection:

• Glyphosate: Glyphosate-based herbicides are effective against Johnson grass, but they are non-selective, meaning they will kill any plant they come into contact with. Use them carefully for spot treatments or in areas where you want to completely eliminate all vegetation. Glyphosate is absorbed through the leaves and translocated to the rhizomes, providing systemic control.
• Selective Herbicides: Selective herbicides, such as those containing sethoxydim or clethodim, are designed to kill grasses while leaving broadleaf plants unharmed. These are a good option for controlling Johnson grass in hay fields where you want to preserve legumes like alfalfa or clover.

Application Techniques:

• Spot Treatment: Use a handheld sprayer to apply herbicide directly to individual Johnson grass plants. This minimizes the impact on desirable forage species.
• Wick Applicator: A wick applicator allows you to apply herbicide to Johnson grass plants without spraying. This is a good option for controlling Johnson grass in sensitive areas or when you want to avoid drift.
• Boom Sprayer: For large infestations, a boom sprayer can be used to apply herbicide over a wider area. However, be sure to calibrate your sprayer properly and use the correct nozzle type to minimize drift and ensure even coverage.

Technical Requirements:

• Herbicide Rate: Follow the manufacturer’s instructions carefully when determining the herbicide rate. Using too little herbicide may result in poor control, while using too much can damage desirable plants and contaminate the environment.
• Application Timing: Apply herbicides when Johnson grass is actively growing and has sufficient leaf area to absorb the herbicide. Avoid applying herbicides during periods of drought or extreme heat, as this can reduce their effectiveness.
• Weather Conditions: Avoid applying herbicides on windy days or when rain is expected, as this can lead to drift and runoff.

My Story: I once made the mistake of applying glyphosate on a windy day. The herbicide drifted onto my neighbor’s vegetable garden, causing significant damage. It was a costly and embarrassing lesson in the importance of following proper application procedures.

Data Point: A study published in the Weed Science journal found that glyphosate applied at a rate of 1.5 lbs acid equivalent per acre provided 90% control of Johnson grass when applied to actively growing plants.

Safety Codes: Always wear appropriate personal protective equipment (PPE), such as gloves, eye protection, and a long-sleeved shirt, when handling herbicides. Follow all safety precautions listed on the herbicide label.

Pro Timber Tip #3: Soil Health Optimization

Healthy soil is the foundation of a healthy hay field. By optimizing soil health, you can create an environment that favors desirable forage species and suppresses Johnson grass growth.

Key Practices:

• Soil Testing: Conduct regular soil tests to determine the nutrient levels and pH of your soil. This will help you identify any deficiencies or imbalances that may be hindering the growth of desirable forage species.
• Fertilization: Apply fertilizer based on soil test recommendations. Use a balanced fertilizer that provides the nutrients needed for optimal forage growth.
• Lime Application: If your soil is acidic, apply lime to raise the pH. Most forage species prefer a slightly acidic to neutral pH (6.0-7.0).
• Organic Matter: Increase the organic matter content of your soil by incorporating compost, manure, or cover crops. Organic matter improves soil structure, water retention, and nutrient availability.

Technical Specifications:

• Soil pH: Maintain a soil pH between 6.0 and 7.0 for optimal forage growth.
• Nutrient Levels: Ensure that your soil has adequate levels of nitrogen, phosphorus, and potassium. The specific nutrient requirements will vary depending on the forage species you are growing.
• Organic Matter Content: Aim for an organic matter content of at least 3%.

Unique Insight: I’ve found that adding biochar to my soil has significantly improved its water retention and nutrient availability. Biochar is a charcoal-like substance produced from burning biomass in a low-oxygen environment. It acts like a sponge in the soil, holding water and nutrients and making them available to plants.

Case Study: In a trial I conducted on a small section of my hay field, I applied biochar at a rate of 1 ton per acre. After one year, the soil in the biochar-amended plot had significantly higher levels of organic matter, water retention, and nutrient availability compared to the control plot. The forage in the biochar-amended plot also showed improved growth and vigor.

Practical Tip: When applying lime, incorporate it into the soil as deeply as possible. This will help neutralize the acidity throughout the soil profile.

Pro Timber Tip #4: Competitive Planting

Competitive planting involves introducing forage species that are highly competitive with Johnson grass. These species can outcompete Johnson grass for resources, suppressing its growth and reducing its spread.

Recommended Species:

• Alfalfa: Alfalfa is a high-yielding, high-protein legume that is highly competitive with Johnson grass. It is well-suited to well-drained soils with a pH between 6.5 and 7.5.
• Orchardgrass: Orchardgrass is a cool-season grass that is highly palatable and productive. It is well-suited to a wide range of soil types and is tolerant of shade.
• Tall Fescue: Tall fescue is a durable, drought-tolerant grass that is well-suited to heavy grazing. However, be sure to select an endophyte-friendly variety to avoid potential toxicity to livestock.
• Clover: Clovers (red, white, and crimson) are legumes that fix nitrogen in the soil, improving soil fertility and providing a valuable source of protein for livestock.

Planting Strategies:

• Overseeding: Overseeding involves broadcasting seed over an existing hay field. This is a good option for introducing new species without disrupting the existing forage stand.
• No-Till Drilling: No-till drilling involves planting seed directly into the soil without tilling. This minimizes soil disturbance and helps conserve moisture.
• Conventional Seeding: Conventional seeding involves tilling the soil, preparing a seedbed, and then planting the seed. This is the most common method of seeding, but it can lead to soil erosion and moisture loss.

Technical Requirements:

• Seeding Rate: Follow the recommended seeding rate for the species you are planting. Using too little seed may result in a thin stand, while using too much can lead to overcrowding and competition.
• Planting Depth: Plant the seed at the correct depth. Planting too shallow can result in poor germination, while planting too deep can prevent the seedlings from emerging.
• Soil Moisture: Ensure that the soil is moist at the time of planting. Dry soil can inhibit germination and seedling establishment.

Personal Insight: I’ve had great success with interseeding clover into my existing hay field. The clover not only helps suppress Johnson grass but also improves the overall quality of my hay.

Data-Driven Tip: A study by the University of Kentucky found that interseeding red clover into a tall fescue pasture reduced Johnson grass biomass by 30% over two years.

Tool Requirements: Depending on the planting method, you may need a no-till drill, a broadcast seeder, or a conventional seed drill. Be sure to calibrate your equipment properly to ensure accurate seeding rates.

Pro Timber Tip #5: Rhizome Disruption and Removal

This final tip is the most labor-intensive, but it can be highly effective for small to medium-sized infestations. It involves physically disrupting and removing the Johnson grass rhizomes from the soil. This is similar to how foresters clear underbrush and root systems during site preparation for reforestation.

Methods:

• Tilling: Tilling can help disrupt the rhizome system, but it can also spread the rhizomes to new areas if not done carefully. Use a chisel plow or a disc harrow to break up the soil and expose the rhizomes.
• Hand Digging: For small infestations, you can dig up the Johnson grass plants and remove the rhizomes by hand. This is a time-consuming process, but it can be very effective if done thoroughly.
• Solarization: Solarization involves covering the infested area with clear plastic during the summer months. The heat trapped under the plastic will kill the Johnson grass plants and rhizomes.

Technical Considerations:

• Tilling Depth: Till to a depth of at least 6 inches to disrupt the rhizome system.
• Rhizome Disposal: Dispose of the rhizomes properly to prevent them from re-establishing. You can burn them, compost them (if they are thoroughly dried), or bury them deeply.
• Solarization Duration: Leave the plastic in place for at least 6-8 weeks during the hottest part of the summer for effective solarization.

My Experience: I once spent an entire weekend hand-digging Johnson grass rhizomes from a small section of my hay field. It was backbreaking work, but it was worth it to eliminate the infestation without using herbicides.

Data Point: Research from Kansas State University shows that solarization can reduce Johnson grass populations by up to 90% when done properly.

Safety Tip: Wear gloves and sturdy shoes when digging up Johnson grass rhizomes to protect yourself from cuts and scrapes.

Tool Calibration Standards: Ensure your tillage equipment is properly calibrated to achieve the desired tilling depth and avoid damaging the soil structure.

Maintaining a Johnson Grass-Free Hay Field

Eradicating Johnson grass is only half the battle. The other half is preventing it from returning. Here are some key strategies for maintaining a Johnson grass-free hay field:

• Regular Monitoring: Regularly inspect your hay field for signs of Johnson grass. The sooner you detect a new infestation, the easier it will be to control.
• Prompt Treatment: Treat any new Johnson grass infestations promptly. Don’t let them get established and spread.
• Seed Quality: Use high-quality, weed-free seed when planting or overseeding.
• Equipment Sanitation: Clean your mowing equipment and other farm machinery thoroughly before moving from infested areas to clean areas. This will help prevent the spread of Johnson grass seeds and rhizomes.
• Border Control: Control Johnson grass along the edges of your hay field to prevent it from encroaching into the field.

Industry Standards: Adhere to best management practices (BMPs) for weed control in hay fields. These BMPs are designed to minimize the impact of weed control practices on the environment and to promote sustainable hay production.

Final Thoughts

Battling Johnson grass is a marathon, not a sprint. It requires patience, persistence, and a combination of strategies. But with the right approach, you can reclaim your hay field and produce high-quality forage for your livestock. These “pro timber tips” that I have shared are what I have learned over the years and what I have found to work.

Remember, every hay field is unique, so you may need to adapt these tips to your specific situation. Don’t be afraid to experiment and find what works best for you. And most importantly, don’t give up! With dedication and perseverance, you can win the battle against Johnson grass and create a thriving, productive hay field.

I hope that my experiences and insights will help you on your journey. Good luck, and happy haying!

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