Grazing Bites by Victor Shelton, Retired NRCS Agronomist/Grazing Specialist Weather has been the biggest variable again this year, and it’s made clear just how different conditions can be from one farm to the next. From my own place in southwest Indiana, we’ve had more rain than we’d like, while others nearby have been dealing with the opposite. No one set of observations covers every situation, so what I share each month comes from what I see at home, along with farm visits, conversations with producers and the questions and challenges you pass along. My goal is to offer ideas and principles you can adapt to your own conditions – rain or shine. Weeds have been especially challenging this year across both pastures and hay fields. Prolonged periods of either excessive rainfall or drought have stressed desirable forage species, opening the door for opportunistic and often toxic weeds to expand. When cool-season grasses and legumes are weakened, weed species are quick to exploit the gaps. This season has seen widespread increases in Carolina horsenettle, nimblewill, ironweed, annual ragweed, cocklebur and Perilla mint, all of which are showing up more frequently and more aggressively than in recent years. Each of these presents its own risks and management challenges. Both excessively wet and droughty conditions can create voids in preferred forage stands, whether through root damage, crown rot, dormancy or reduced regrowth. These openings are quickly exploited by opportunistic weeds, many of which have been lying dormant in the soil seed bank, waiting for the right conditions to emerge. Annual species like ragweed and cocklebur in particular are well-adapted to take advantage of bare soil and reduced competition, establishing quickly and spreading aggressively in stressed pastures and hay fields. This year’s hot, wet summer created ideal conditions in many areas for nimblewill (Muhlenbergia schreberi) to thrive across pastures, hayfields and lawns. As a warm-season perennial grass, nimblewill takes full advantage of hot temperatures and ample soil moisture – particularly in shaded, low-lying or poorly drained ground. In these favorable areas, cool-season grasses and legumes often went dormant or struggled with disease pressure, thinning out and leaving gaps that nimblewill quickly filled. Even pastures with good fertility saw increased spread, as the grass’s creeping stolons rooted easily in soft, saturated soils. Managing nimblewill going forward will require a combination of strategic grazing, fertility management and timely reseeding. High-density, short-duration grazing (mob grazing) or targeted bale grazing during winter can help suppress existing stands by trampling growth and improving soil structure. Fall remains the best opportunity to overseed thin or infested areas with cool-season grasses and legumes. Soil testing and applying the correct balance of phosphorus, potassium and lime will support strong regrowth of desirable species, helping them compete more effectively. While nimblewill may not be eliminated entirely, it can be pushed back with consistent pasture management that prioritizes dense, vigorous forage. Addressing compaction, improving drainage and rotating pastures thoughtfully are all key to keeping this opportunistic invader in check – especially as weather extremes become more common in the years ahead. Another pest with a growing footprint is perilla mint. I first remember encountering perilla mint back in the 1970s on a farm I knew well. You usually smelled it before you ever saw it – that sharp, pungent, minty odor that filled the air when the plant was brushed or disturbed. Back then, it was mostly a plant of the woods edge, showing up along fence lines, in lightly grazed wooded areas or in spots where cattle had opened the understory a bit. It kept to the shadows, and you rarely saw it out in the open. Fast forward to this year, and perilla mint is showing up in places it never used to – even in full sun. This shift is concerning, not just because it signals the plant is adapting to a wider range of conditions, but because of the serious toxicity risks it poses to livestock. All parts of the plant – especially the seeds – contain perilla ketones, which can cause fatal respiratory distress in cattle, horses and other ruminants. There’s no antidote, and symptoms often appear suddenly, including labored breathing and reluctance to move. Perilla mint takes advantage of disturbed or thin pasture ground, thriving where preferred forages have been weakened by drought, trampling, overgrazing or excess moisture. Once it finds a foothold, it can spread rapidly – especially in late summer – making it all the more important to scout regularly and take control measures before seed set. Mowing, targeted herbicide use and maintaining dense forage cover are key strategies to limit its spread. Given its toxicity and increased presence across a wider range of conditions, perilla mint can no longer be viewed as just a woods-edge nuisance, it’s a pasture management priority. It’s considered safe to pull perilla mint by hand when individual plants are found, especially far from wooded or shaded areas – though you might want to wear gloves, if only to avoid carrying that strong, lingering minty smell with you all day. When it comes to deciding whether to use mechanical or herbicide treatments for pasture weeds based on how much canopy they cover, a good rule of thumb is that once weeds hit around 20 percent coverage, it’s usually time to act. If they’re under 10 percent, mowing or adjusting grazing often does the trick, and between 10 and 20 percent, it’s worth keeping a close eye and maybe spot-treating, especially if the weeds are aggressive or toxic. I used to lean toward waiting until 30 percent coverage before jumping to herbicides – and honestly, that might still be OK sometimes. It depends on the type of weed and whether your livestock will eat it, since some weeds can be surprisingly nutritious. It’s all about balancing how competitive and toxic the weeds are with how useful they might be for your animals. For areas with adequate moisture this year, the classic mix of oats, a brassica such as turnips or radish, and cereal rye can deliver exceptional grazing benefits. The oats and turnips mature early, providing high-quality forage that can be grazed comfortably well into December or beyond. Then, the cereal rye kicks in during spring, offering additional grazing or forage harvest opportunities before fields return to row crops. When grazing cereal rye ahead of cropping, it’s best to do so on dry or frozen soils to avoid compaction. This rotation also allows fall pastures more time to recover before going dormant, supporting healthier, more productive stands. It’s not about maximizing a single grazing event but optimizing the entire grazing season. Observe, plan ahead and keep on grazing. Reminders & Opportunities Greg Brann’s Regenerative Farm-Pasture Walk – Oct. 16, 2025 - 683 Blankenship Rd, Adolphus, KY – 11 AM-5 PM ET - $45 per person for the event. https://gregbrann.com/pasture-walk-2025/ Please send comments or questions to grazingbites@gmail.com. |
