1Kurt Vollmer, Weed Management Specialist | kvollmer@umd.edu and 2Mark VanGessel, Weed Management Specialist 1University of Maryland Extension and 2University of Delaware
The shortage of glyphosate (Roundup, Gly Star, etc.) and glufosinate (Liberty, Interline, etc.) herbicides are forcing farmers to seek other options for burndown and postemergence spray. No one anticipated this shortage and very little research has been done to address this issue. Many of us had to dust off our notes from the early 1990’s, the time before cheap glyphosate was available. One thing is certain, alternative weed control options will require more targeted management. The key is to plan ahead, select herbicides based on the weeds in the field, and make timely applications. Your mindset needs to be that you are not substituting a herbicide for glyphosate, rather you are using a different herbicide that has its own set of recommendations and limitations.
Alternative herbicides will not control as many weed species as glyphosate; in fact, some are only effective on a few weed species. Weed populations differ from field to field, so it is likely that herbicide mixtures will need to be adjusted for specific fields. Scouting will be key to selecting the right herbicide combination for a particular field. Scouting should be performed multiple times during the growing season to identify the species present and be sure weeds are small at time of application. In addition, it is important to check after a treatment is made to be sure it was effective.
Field records and past experience will help you decide which fields to prioritize for treatment with glyphosate or glufosinate. Targeting those “problem” fields or fields that will be rotated to vegetables for glyphosate or glufosinate applications.
Making Glyphosate Go Further
Use the correct glyphosate rate for the situation. In the past few years, many have simply used a quart of glyphosate (regardless of brand) because it was easy and still quite cost-effective. Matching the rate based on formulation and weed size will help conserve glyphosate and allow more acres to be treated. The amount of glyphosate in formulated products ranges from 41% to 51.2%. In practical terms, the rate of various brands can vary widely. For example, the Roundup PowerMax 3 rate for most annual weeds is 20 fl oz, while the same amount of glyphosate in a popular generic version is 32 fl oz.
Also, using glyphosate at higher use rates often overcomes issues that could reduce performance. So be sure to review the label for recommended adjuvants and any tank mixtures to avoid.
Start Clean
“Starting clean” means weeds are dead at planting. This is important since it is difficult to control many species like horseweed or Italian ryegrass after planting. Spring tillage is an option for replacing burndown herbicides; but tillage can negatively impact soil health, and stimulate the emergence of weeds such as common ragweed and Palmer amaranth.
For no-till corn, paraquat plus atrazine or paraquat plus simazine have worked very well on most of our acreage, including fields with horseweed and seedling grasses. One exception is Italian ryegrass, and this is a situation that may warrant using glyphosate.
For no-till soybeans, which are often sprayed 2 to 4 weeks later than corn, winter annual weeds will be larger and more challenging to control. Paraquat plus metribuzin is effective on smaller broadleaf weeds. Back in the ‘90’s when glyphosate was too expensive to spray across all acres, sequential applications of paraquat were commonly used. The recommendation was to use paraquat plus metribuzin 2 to 3 weeks before planting and then a second application at planting with the residual herbicides.
Fields with “problem” winter annual weeds may need an early herbicide application followed by an at-planting treatment. Herbicide options for soybean burndown include Sharpen, Elevore, 2,4-D or dicamba for horseweed; Canopy EX plus 2,4-D for field pansy and primrose control; metribuzin for chickweed and henbit; and Select (clethodim) for grass control (although clethodim is weak on annual bluegrass). Tankmixing broadleaf herbicides such as 2,4-D or dicamba with clethodim can reduce grass control; using higher rates of clethodim and spraying smaller grasses can reduce the likelihood of antagonism. The alternative is to separate applications. Clethodim and other grass herbicides should be made 2-3 days before or 7 days after a broadleaf herbicide.
Paraquat plus metribuzin is useful for terminating cover crops, including legumes and brassicas. Paraquat is more effective for terminating winter wheat or cereal rye when it is applied at the boot stage or later. Delaying cover crop termination until 7 to 14 days before planting will enhance overall weed control by allowing more cover crop biomass to form, which results in fewer weeds emerging and slowing the growth of emerging weeds. Paraquat applications before the boot stage often allow cereals to regrow. Clethodim could be used to control cereal cover crops before the boot stage.
Burndown for double-cropped soybeans will also be challenging without glyphosate and/or glufosinate. Paraquat and 2,4-D are not good options as they are more likely to move off-target that time of year. This may be another situation that gets priority for glyphosate and/or glufosinate applications.
Include Residual Herbicides at Planting
A good residual program will help delay a postemergence herbicide application. Two or more herbicide groups will be needed to provide broad-spectrum control of all the potential weeds that may emerge. A corn program should include at least atrazine and a group 15 herbicide such as S-metolachlor or acetochlor. Using products that include group 27 herbicides (Balance Flexx, Acuron, Corvus, Lumax) can also help.
A soybean program should include at least two effective herbicide modes-of-action from group 14 (Valor, Authority), group 5 (metribuzin), group 15 (Dual, Warrant, Zidua), or group 3 (Prowl). Group 15 herbicides provide good grass control and can reduce the likelihood of needing to treat postemergence with a product such as clethodim (Select) or sethoxydim (Poast). Several prepackaged mixtures of these herbicides are also available but be sure to check to ensure they are the appropriate rates for your situation. Regardless of what programs are chosen, an activating rainfall of about half inch will be needed.
Make Timely Postemergence Applications
Postemergence control is more successful with small weeds; thus avoiding the urge to wait for all weeds to emerge prior to spraying or cultivating. Corn is most susceptible to yield loss from weed competition during the V1 to V6 growth stages, and soybean at the V1 to V5 growth stages.
Because it is cooler during the early stages of corn growth than soybeans, it creates a wider window of application for corn. Postemergence treatments in corn are more effective when corn is less than 12 inches tall because it allows the use of atrazine. In corn, group 27 herbicides such as Armezon, Callisto, or Laudis plus atrazine provide effective control of weeds like Palmer amaranth. Impact, Armezon, and Accent Q will provide good to excellent control of most grass species.
Postemergence herbicide applications in soybeans are most effective when soybeans have less than 4 trifoliates, and weeds are less than 4 inches tall. In local research, this is typically 3 to 4 weeks after planting. In soybean, postemergence herbicide options will be trait-dependent. Group 14 herbicides such as Cobra, Reflex, and Ultra Blazer can be used in non-GMO soybean. Dicamba-containing products such as Xtendimax, Engenia, or Tavium can be applied to Xtend and Xtendflex soybeans; and 2,4-D choline (Enlist One, Enlist Duo) can be applied to Enlist E3 soybeans. Glufosinate and glyphosate-based products can also be applied to Enlist E3 and Xtendflex soybean. If planning to use these products, growers need to be aware of restrictions as well as specific requirements for adjuvants, nozzles, buffers, etc. which can be found at
Residual herbicides such as Dual, Warrant, or Zidua can be included with postemergence treatments to help extend weed control capabilities until the crop canopies. (note: Reflex provides both postemergence and residual control). This will be cheaper than making multiple postemergence applications.
Optimize Herbicide Performance
It is important to maximize the performance of herbicides and most of this information is available on herbicide labels. Adequate spray coverage is important for contact herbicides like glufosinate and fomesafen. Applications of contact herbicides should be made at 15 to 20 gallons per acre with nozzles that produce medium to coarse droplets to ensure good coverage. Growers should also follow recommendations for adjuvants.
When tankmixing herbicides it can be challenging if recommendations differ by product, such as droplet size does not match or required adjuvants may differ. For instance, Enlist One requires large droplets to avoid drift while a contact herbicide, like Reflex, recommends smaller droplets to improve spray coverage. In this case, select a nozzle from the Enlist label that produces the smaller droplets.
Environmental conditions such as temperature and time of day will also affect the performance of herbicides. In particular, conditions during burndown applications can be challenging; and if applications are made during poor growing conditions, control is often reduced. There are very few alternatives to waiting for better weather. Generally, contact herbicides such as paraquat and fomesafen are more effective when sunlight is more intense. Glufosinate has specific recommendations for applications between the hours of 10 AM and 2 PM to ensure there is adequate sunlight to maximize performance.
Including other tactics to reduce weed competition can enhance an effective herbicide program. A healthy, competitive crop will reduce late-season weed emergence. The quicker a crop canopy develops, the less likely it will be for additional weeds to emerge. Reducing soybean row spacing from 30 to 15 inches will allow for quicker canopy closure. A timely cultivation can replace a postemergence herbicide application in fields with light weed pressure.
Preparing ahead of time and considering all the options will help ensure the highest level of weed control. Have a conversation with your crop advisor on which options are best for your fields and focus on managing small weeds.
Cerruti R2 Hooks$ and Dwayne Joseph* $Professor and Extension Specialist, *Post-Doctoral Fellow, CMNS, Department of Entomology
INTRODUCTION
Mowing is a relatively inexpensive mechanical weed management option that imposes minimal disturbances to the soil. Several types of commercial mowers including rotary, flail, reciprocating sicklebar and reel can be used to suppress weed growth. Still, mowing is generally not thought of as a formable integrated weed management (IWM) tool as it is not congenial to most cropping systems or all land types. For instance, having a smooth soil surface free of rocks or other obstructions is a necessity for mowing operations, and if mowing close to the ground, the soil surface should be even. Some have declared that mowing is primarily used to limit seed production and restrict unsightly weed growth in un-tilled herbaceous and woody perennial crops. It is important for managing vegetation in pastures, meadows, rangelands, grassed waterways, field margins, turf, orchards, tree plantations, vineyards, golf greens and lawns as well as conservation reserve land and roadsides (Fig. 1). In conservation ecology, mowing may be used to shift plant succession and encourage native plant establishment while discouraging undesirable vegetation. In some non-cropping environments, the mower is used primarily for aesthetic reasons. Still, preventing weeds from reaching maturity beyond crop fields is of critical importance as it can prevent these areas from serving as nurseries for weed proliferation. For example, several species of arable weeds are frequently present in field boundaries such as road verges and some can colonize and reproduce in crop fields. Mowing can be deployed to prevent these and other weeds from producing seeds. However, mowing is ineffectual in destroying vegetative (asexual) structures such as rhizomes (below ground stems), stolons (above-ground stems) corms, tubers and bulbs in which very small structures may result in a new plant. This suggests that mowing may not be compatible with all weed types. Still, it can contribute to an IWM program especially if used in concert with other management tactics.
Fig. 1. Transportation maintenance specialist mowing an interstate roadside. Attribute: Oregon Department of Transportation (CC).
MOWING EFFECTS ON WEEDS
Mowing defoliates plants and because leaves collect carbon dioxide and sunlight, defoliation alters their competitive ability. Mowing can reduce weed vigor, growth, survival and reduce or prevent seed production. Mowing kills existing shoot growth. However, mowed plants can produce additional shoot material and there is also potential of new stem development from previously dormant lateral buds. Still, this may be desirable as new stems grow at the expense of below-ground stored food. As such, repeated cutting hastens food depletion and death of some plants. Under frequent mowing, a plant must generate enough photosynthates under limited leaf area to fuel normal plant function while not depleting carbohydrates stored within the roots. Mowing can also delay flowering of some weed species and impact weeds indirectly by changing their environment. For example, light, temperature and soil moisture among other abiotic factors may change in a mowed plant community. This can occur because mowing creates vegetative gaps by removing plant parts that form a canopy and shades the soil surface. As a result, light intensity and quality changes at the soil surface. Further, the average daily soil temperature and diurnal temperature range at the soil surface increases. These abiotic changes on the ground can favor the germination or emergence of one or more weed species that would have otherwise remained dormant or suppressed. Plant residue that remains after mowing may also change abiotic conditions at the soil surface and subsequently influence the weed community. Mowing also changes the competitive relationships between neighboring weeds and other plants because different plants are impacted varyingly by mowing, some may die or regrow at different rates. As such, mowing can change the flora in an area. Thus, understanding how mowing impacts the biology of different weeds is important as it can be used to manipulate a plant community so that it favors native or other desirable plants.
WHEN to MOW
Fig. 2. Plumless thistle, Carduus acanthoides Attribute: Andreas Rockstein (CC)
Properly timed mowing can suppress unwanted vegetation while favoring desired plant flora. Integrated weed management should target the susceptible stages in a weed’s life cycle and if mowing is being conducted to prevent seed production, it should always be done prior to flower formation. Mowing weeds during this stage can weaken them as they have invested a lot of energy into producing reproductive structures. Mowing to limit weed seed production is usually initiated well after mowing designated to minimized weed-crop competition and yield reductions. Oftentimes, a single mowing will not prevent seed production. New stems below the initial cut can flower and produce seeds. Thus, two or more mowing may be required to inhibit seed formation. However, some weeds such as common ragweed are able to survive repeated mowing. As a general rule of thumb, if only one mowing per growing season is allowed, it should be timed to match weed flowering. Certainly, mowing can be challenging when several weeds with different flowering phenologies co-infest the same site. For instance, mowing timed to prevent viable seed production of one weed species may fortuitously be timed to spread viable seeds of other species. This suggests that tradeoffs may persist when multiple weed species are present in a habitat and mowing is the option. Further, developing seed heads should be mowed before viable seeds are formed. Thus, timing is critical and should precede anthesis, pollination and fertilization. Some viable seeds can form less than 7 days after anthesis. For example, mowing musk thistle within 2 days after anthesis prevented viable seed production. However, mowing was ineffectual if it was conducted 4 or more days following anthesis. The production of viable seeds can occur so instantaneously that if weeds are not mowed before flowering, the benefits may only be cosmetic, especially if the delay results in more weed seeds being deposited into the soil seed bank. Still, variation exists among weed species relative to the best phenological stage to mow. For example, a six-year study in MD found that mowing plumeless thistle (Carduus acanthoides; Fig. 2) at the full bloom stage reduced plant densities compared to mowing it at the full bud or post bloom stage. In the same study, musk thistle (Carduus nutans; Fig. 3) declined only when mowed after the bloom stage. Some weeds have the ability to compensate for mowing effects. They may deploy several strategies to survive mowing such as increasing their photosynthetic rate and tillering, and obtaining greater nutrients.
Fig. 3. Musk thistle, Carduus nutans Attribute: Gertjan van Noord
Properly timed mowing helps minimize weed re-infestation, population increase and seed dispersal of new weed species within fields or from field borders into neighboring crop fields. If mowing is poorly timed, it can spread viable weed seed including herbicide-resistant weeds beyond the current field of infestation. Weed seed dispersal by mowing has been reported to be greatest when mowing and seed set coincide. A study showed that early mowing of chervil (Chaerophylum aureum L.), a weed that infests pasture, reduced seed production by decreasing shoot density and seed set. However, mowing it later resulted in seeds spreading outside the study site. Relative to this, some studies have shown that mowing practices can enhance seed dispersal of some weed species especially those that are favored by disturbances. Mowing may spread weed seeds by blowing them from the mowed area or transporting them on different mower parts. Thus, cleaning mowers between sites may help prevent weed spread.
Fig. 4. Common ragweed (Ambrosia artemisiifolia). Attribute: F. D. Richards (CC)
The regularity of mowing weeds is partially contingent on their tolerance to mowing which is a function of their growth rate, foliage replacement ability and its potential to increase photosynthesis to compensate for leaf loss following mowing. Further, multiple mowing will be required to mitigate seed production if weeds being targeted set seed or emerge in flushes over an extended time period. However, for weeds such as common ragweed, time of mowing and stage of growth may be more important than mowing frequency. Common ragweed can tenaciously regrow after most of its above ground tissues has been removed (Fig. 4). A study demonstrated that despite a substantial loss in aboveground plant tissue, surviving ragweed plants were able to reach the flowering stage after four clippings during the growing season. Similarly, spotted knotweed (Centaurea stoebe) produced tillers and flowers following 3 clippings in a single summer.
Mowing height is also critical as the blades must be low enough to cut off developing seed heads. However, if plants are initially mowed too low, later forming seeds may develop so close to the ground that a second mowing misses them. In addition, conditions may favor the regrowth of mowed weeds. Some annuals such as horseweed will sprout new stems below the cut. This growth may be managed by cutting high at the initial mowing and markedly lower at the next mowing so as to cut off any stems that have sprouted. This strategy is most effective if by the second mowing, the stem is hard and woody, and incapable of developing new sprouts beneath the cut.
MOWING and PERENNIAL WEEDS
Perennial weed control can be costly as well as time consuming. Perennial weeds are typically managed with herbicides and/or aggressive tillage. However, being dependent on herbicides to suppress perennial weeds encourages the development and spread of herbicide-resistant weeds; and an intensive tillage program increases the risk of soil erosion and on-farm energy use. A primary reason that perennial weeds are so resilient is their ability to store reserves in their underground storage organs. This allows above ground regrowth to occur after disturbances. Additionally, the resources in these storage organs are passed on year after year. As such, control measures should target and destroy the underground storage network or disrupt them by reducing or eliminating their ability to translocate resources formed during photosynthesis to other plant parts. Tillage can be used to weaken and destroy the underground storage organ. If it weakens it, the plant becomes more susceptible to other management tactics such as growing a competitive crop and mowing. As such, management tactics that are timed to deplete the food reserves of perennials are most likely to prevent regrowth and spread. For example, the lowest root carbohydrate reserves in Canada thistle occurs just before flowering, when the plant is in the “bud to bloom” stage. Repeated mowing coupled with a competitive crop can deplete carbohydrates reserves from Canada thistle roots and frequent mowing can kill young shoots before they replenish their reserves.
In addition to preventing seed production of perennial weeds, repeated mowing may starve their underground parts. Cutting the leaves and other above ground plant parts reduces biomass accumulation and eliminates the food producing organs as photosynthesis occurs within the leaves, although in some instances, photosynthesis occurs within the plant’s stem. Regrowth that occurs following a cutting drains sustenance from the stored food supply of the weed. As such, repeated mowing can reduce reserves housed in the storage organs. Still it is important to note that using this repeated mowing protocol may not result in the quick death of a perennial weed patch. Effective mowing of large infestations may be a long-term commitment. It may require two or more years of repeated mowing to fully kill a perennial weed stand. The best time to initiate mowing is generally when the underground root reserves of weeds are at a reduced level. This generally occurs when weeds are between full leaf development and flower occurrence. Interestingly enough, these tips related to mowing time can be applied to the timing of herbicide applications for managing perennial weeds as these weeds may also be most vulnerable to herbicides during this stage of their development.
In perennial crops such as forages, weeds and crops are mowed concurrently. The aim is usually to suppress weed competition and seed production while harvesting and managing crop biomass and maintaining pleasing aesthetics. In non-cropland habitats such as field borders typically perennial vegetation is mowed to maintain ground cover and prevent erosion. When crops are planted in rows such as orchards and fruit tree systems, weeds and other vegetation between crop rows are mowed to limit competition with the crop. However, it is important to maintain a stand of “beneficial” vegetation in the inter-row areas as this helps prevent erosion.
MOWING and COVER CROPPING
Crops are sometimes planted without tillage into terminated cover crops. Relative to weed control, the main purpose of the “leftover” cover crop residue or mulch is to suppress weeds within the crop row. To this point, weed control in the between row area may be inadequate in a mulch system especially if the crop is not planted at narrow row spacing and/or the biomass of the residue is inadequate. This is more of a problem in the between row area because the crop’s canopy may not contribute to shading the soil in this area. This suggests that overall weed suppression in a mulch system may be more satisfactory if weeds in the between row area can be subjected to an additional management tool. Fortunately, several implements such as high-residue cultivators exist and can be readily used in established crop fields with cover crop residue without jamming (Fig. 5). Mowing can also contribute to weed suppression in a mulch system. Relative to this, a study examining cultivation as a weed suppression tool in a herbicide-killed rye mulch system found that two inter-row cultivations provided adequate weed suppression in dry beans when field margins were mowed to prevent seed production by dandelion, Taraxacum officinale.
Fig. 5. A) Cultivator operating in bean field with rye cover crop. Attribute: agriculture.hiniker.com & B) High-residue cultivator. Attribute: Univ. of Delaware Carvel Research & Education Center, M. Walfred
Mowing typically contributes to short term weed suppression. As such, it may only be effective in a fast-growing crop particularly one in which a cover crop mulch has restricted weed establishment. Notwithstanding, in some situations, mowing can reduce the effectiveness of a mulch by speeding up its decomposition. Mowing clips cover crops into smaller pieces which break down more rapidly than thick mats. Differences in mowed residue fragment size and decomposition rate influence the duration of residual weed control from cover crop residue. For example, mowing residue (e.g., barley, crimson clover, hairy vetch, rye, subterranean clover) with a sicklebar at or after the mid- to late-bloom stages suppressed yellow foxtail, common lambsquarters, and redroot pigweed better than flail mowing (Fig. 6). It is believed that this occurred because flail mowing left smaller fragments of residue on the soil surface. Though mowed cover crop residue can provide some weed suppression, the duration and level of weed control by mowed residue is inconsistent and often will not provide good suppression the entire cropping cycle.
Mowing may also be done in concert with a living mulch (e.g., cover crop that lives the entire duration of the crop life cycle). A study found that mowing buckwheat living mulch between tomato rows after the critical weed control period suppressed weed seed production. The critical period for weed control is the period in the crop growth cycle during which weeds must be controlled to prevent unacceptable yield losses. A field experiment was conducted in Illinois to study the combined effect of mowing and growing a summer annual cover crop on Canada thistle growth. The study showed that a sudangrass or sudangrass-cowpea mixture alone or combined with mowing suppressed Canada thistle shoot density and mass to less than 20% of initial shoot and mass compared to buckwheat or fallow treatments. However, intensive management must be continued for several years to eliminate patches.
INTEGRATING MOWING with HERBICIDES
Several investigations have been conducted to examine impacts of combining mowing with other weed management tactics. Relative to this, a between row mowing tactic in combination with herbicide applications and crop canopy shading was evaluated in soybean and field corn. The investigation showed that if properly timed, mowing weeds located in the between row area close to the surface < 3.8 cm (1.5 inch) two or more times can kill or suppress annual grass and broadleaf weeds, such as giant foxtail, common ragweed and waterhemp species. During the investigation, weeds within the soybean rows were managed with herbicides and those that “escaped” treatment were suppressed by early crop shading and competition. It was suggested that this management strategy which consists of a) planting a competitive crop, b) banding herbicide(s) over the crop row and c) mowing weeds between crop rows close to the soil surface before crop canopy closure can be successfully used in competitive crops such as corn, soybean and grain sorghum which closes their canopy and shade weeds early in their cropping cycle. Thus, the implementation of husbandry practices that enhances crop competitiveness with weeds is critical to the success of this management plan.
Unfortunately, between row mowing is not adaptable to most cropping systems especially those grown in very narrow row spacing (e.g., drilled grain) and are weakly competitive and lack the ability to form a closed canopy. In addition, many producers will lack the equipment needed for mowing between crop rows. However, if it can be used in combination with herbicides, it is expected that the amount sprayed can be reduced by 50 percent or more as sprays are only banded within the crop row. Mowing has also been investigated for its ability to supplement herbicides and cultivation in peanuts. After weeds had grown 20 cm (7.9 inch) above the peanut canopy, a tractor pulled rotary mower was used to cut off seed heads just above the canopy 8 and 13 weeks after planting. The mowing prevented peanut shading by bristly starbur, sicklepod and Florida beggarweed. Mowing and applying herbicides in the within row areas of citrus trees are the most widely used weed control practices in Brazil. However, a three-year study in Brazil indicated using ruzi grass, Urochloa ruziziensis as a cover crop, combined with within row glyphosate and an ecological mower is a more sustainable IWM option for citrus trees. An ecological mower cuts the cover crop in the between row areas and the resulting residue is launched within the crop rows. Eco-mowing, which involves placing the cuttings from cover crops under the canopies of citrus trees rather than leaving them in the middle rows, is also being researched in Florida.
A study was conducted to test whether integrating early season mowing with a systemic herbicide application would improve the control of perennial pepperweed (Lepidium latifolium, Fig. 7). Mowing alone did not reduce weed biomass or its density the following year. However, mowing followed by application of an herbicide to re-sprouting plants reduced biomass in three different environments (high desert, roadside and floodplain habitats). The combination of mowing and the herbicide, chlorsulfuron reduced pepperweed biomass > 99% at all three sites and glyphosate + mowing > 80% at two sites, one year after application. It was noted that an initial mowing increased the effectiveness of glyphosate to a level where it became an effective control option.
Fig. 7. Perennial pepperweed (Lepidium latifolium) an invasive noxious weed. Attribute: J. N. Stuart (CC).
ADVANTAGES OF MOWING
Mowing may be repeated over a longer period than some herbicide treatments or cultivation. Further, mowing can be used to suppress weeds that have become too large to be managed with herbicides or cultivation; and mowing has fewer off site environmental effects. Thus, it can be an option where ground cover is desired and herbicide use would be restricted or undesirable. Mowing may also be used in circumstances where concerns exist regarding herbicide contamination of water bodies. Mowing can also be used during situations where weather conditions such as wind speed causes herbicide drift or reduces its efficacy. To this point, mowing is advantageous in highly populated or suburban housing areas where the public is concerned about herbicide exposure. Mowing can be used as a substitute in field conditions where cultivation might damage root systems or lead to soil erosion. Mowing limits erosions caused by wind and water by allowing live vegetation and plant residue to remain on the soil surface. Moreover, mowing is compatible with other soil and plant conservation measures such as no-till practices and land conservation programs. Fields can also be mowed faster following a heavy rainfall event compared to cultivation which requires much drier soil conditions.
NEGATIVE ASPECTS of MOWING
Weed species vary in their response to mowing height and frequency and some readily accommodate mowing. “Weeds adapted to mowing tend to grow short, in a rosette form, creeping above the soil surface or show high plasticity and softness of aerial parts and stems and become difficult to mow and also escape hand weeding.” Thus, if multiple weed species of varying height persist in a habitat, mowing may become more of a challenge. Mowing can favor weeds that develop and reproduce below the mowing height and repeated mowing of similar weeds can cause a shift: 1) in biotype from an upright growing form to a more prostrate form, and 2) to a community of weeds that are tolerant to mowing. For example, mowing was correlated with differences in plant size and degree of erectness caused by genetic differences between mowed and un-mowed broadleaf plantain (Fig. 8). This suggests that an integrated or more holistic approach should always be the goal of any weed management program as weeds will adapt to a single management approach. Further, though mowing may reduce aboveground competition, if it fails to kill weeds, they may still compete with crop plants for resources such as space, nutrients and water below the soil. Moreover, weeds that form rosettes or mats and/or grow close to the ground are naturally adapted to mowing. This is why weeds such as dandelion, bermudagrass, crabgrass, goosegrass and buckhorn plantain, once established, are immune to mowing. Additionally, wheel traffic that occurs during mowing can compact some soils such as silty clay loam. Mowing can also be noisy and though vegetation remains on the surface, it may still raise dust.
Fig. 9. Buckhorn plantain (Plantago lanceolata). Attribute: Clemson University Extension
Mowing is a relatively inexpensive form of mechanical weed control that can reduce the use of tillage, herbicide and manual weeding. It may serve as an alternative to herbicide and cultivation or part of an integrated approach. However, mowing to manage weeds has not been well studied compared to other IWM tools and is more popular in habitats with perennial stands of vegetation. Consequently, limited information is available on mowing use in crops. As such, it is not adaptable to numerous cropping systems; and partially for this reason, it is used mainly for aesthetic reasons and preventing seed production in perennial stands of vegetation neighboring cropland. Still, research has shown that mowing can be used jointly with other weed management tools such as applying herbicides, cover cropping and growing competitive crops. Mowing may also be used to successfully manage perennial weeds by removing the aboveground plant parts and consequently reducing food reserves in their storage organs. This, however, may take multiple years and the integration of other weed management tactics. Some research has found that combining mowing with herbicides enhances perennial weed control. Still, there are advantages and disadvantages of using mowing as a weed management tool. Mowing generally does not have any negative environmental effects. However, many weeds especially those that grow close to the ground such as buckhorn plantain are naturally tolerant of mowing (Fig. 9). As with any IWM program, it is important to “keep weeds guessing” by utilizing different management tactics; and mowing is no exception to this rule. For example, repeated use of mowing as a single weed management tactic may result in a selection pressure or shift to weed species or genotypes that can reproduce even if repeatedly mowed. These species may overtime become more difficult to manage. As such, in those situations where mowing is practical, one should consider making it part of an overall IWM program. Financial support for the publication of this article is via USDA NIFA EIPM grant award numbers 2021-70006-35384 and NESARE – Research for Novel Approaches (LNE20-406R).
A series of workshops will be held in March for farmers interested in learning how to use integrated weed management (IWM) techniques to control troublesome weeds in their fields. This is the fifth year for the workshop series, which is a collaborative effort between the University of Maryland, Virginia Tech, and the University of Delaware.
Education regarding weed identification and integrated management strategies continues to be critically important to enable early intervention and effective management options. 2022 is shaping up to be especially challenging with anticipated shortages of many commonly used herbicides. The 2022 workshop series will provide tactics to manage important weeds given limited herbicide availability and increased input prices. Material covered will target row-crop production systems, but tactics learned may be applicable to other systems. Specific dates, times, and locations for each workshop will be as follows:
March 10: Ag Service Center, 26737 Radio Station Way, Leonardtown, MD 20650 from 8am-1pm;
March 14: Sudlersville Volunteer Fire Department, 203 N Church St, Sudlersville, MD 21668 from 8am-1pm;
March 15: Olde Dominion Agricultural Complex 19783 US Highway 29, Ste. G. Chatham, VA 24531 from 12pm-5pm;
March 24: Virtual via Zoom from 8 am-11am.
These workshops are free, but participants will need to register at https://go.umd.edu/IWM.
Pesticide credits will be available for MD, DE, and WV. Two hours of CCA continuing education credits will be offered for each session.
For more information, contact Kurt Vollmer at (443) 446-4260 or Ben Beale at (301) 475-4481.
This meeting will cover timely topics related to corn, soybean, and small grain production in Maryland. Hear from University of Maryland and other regional experts covering topics, such as:
Weed management with a limited toolbox
Hedging your bets to maximize profitability of fungicides on corn and soybeans
Agriculture leasing and agriculture law update
Corn nitrogen use following cover crops
Soil fertility and 4R
This meeting satisfies credits for pesticide applicator and nutrient management voucher renewals.
Kurt Vollmer, Weed Management Specialist | kvoller@umd.edu University of Maryland Extension
Lately, I have seen several fields with Palmer amaranth flowers (Figure 1). It is imperative that these plants be managed before harvest (Palmer amaranth is listed as a noxious weed in Maryland and Delaware). At this point, mowing or herbicides will not improve yield nor prevent Palmer from germinating next year. Plants need to be physically removed from fields. Palmer amaranth has both male and female flowers on separate plants (Figure 2), and focus should be placed on removing the seed-producing females first. A single female can produce approximately 600,000 seeds per plant, and these seeds can remain viable for six years. Palmer seed matures within 2 weeks of flowering and if left unchecked, a single plant can infest an entire field within a few years (Figure 3).
Figure 1. Palmer amaranth emerging through a soybean canopy.Figure 2. Female plants (left) can be distinguished from male plants (right) by the presence of sharp floral bracts whereas male flowers are soft to the touch.
Upon removal, plants should be bagged and buried or burned along the field’s edge, or disposed of in a manner as to not contaminate other areas. Palmer retains most of its seed in the fall. There is still time to remove them, but combines will spread seed. If plants cannot be removed before harvest time, areas with Palmer should be harvested last, and the combine thoroughly cleaned before moving. Be sure to mark areas where mature Palmer is present, and pay special attention to those areas next year. Taking these measures will help to reduce the Palmer seedbank and prevent the problem from becoming worse next year. In the United States, Palmer is resistant to at least 5 different herbicide groups. So far, Palmer is only resistant to 2 herbicide groups in the Mid-Atlantic. However, any escapes could indicate possible resistance. Let’s not allow any more Palmer to proliferate!
Figure 3. Number of Palmer amaranth escapes possible over successive years.
Reports are for crop conditions up until 8/5/2021.
Western Maryland
We had a great wheat harvest and many optimists planted double-crop beans. It has been very dry in most of the county. Depending on where in the county you are located is the difference between chopping corn now and admiring your crop. Hay will be in short supply so many will plant forage oats for fall forage. Full season beans are looking good most places. We will continue to pray for rain. —Jeff Semler, Washington Co.
Central Maryland
In general, Central Maryland has had a good combination of heat and rain, and the crops are looking great. Most of the region is close to or above the normal rainfall over the last 30 days. Fall armyworm and western bean cutworm traps near Poolesville have been empty this past month. Corn silage harvest will begin soon, especially if August turns up the heat.—Kelly Nichols, Montgomery Co.
Northern Maryland
We’ve been fortunate to have excellent pollination conditions over the past 3 weeks when the vast majority of the corn crop was pollinating. Temperatures were in the upper 80s and occasionally low 90s with frequent storms that brought timely moisture. The majority of the corn crop is looking above average. Full season soybeans are beginning to set pots and look good; some fields had very spotty emergence due to slug damage early; we will see what August brings in terms of rain to help make the bean crop. Double crops had good soil moisture to germinate and are off to a decent start. Insect and disease pest pressure in both corn and beans has been minimal so far. Small grain harvest wrapped up a couple of weeks ago with big wheat yields.—Andy Kness, Harford Co.
Upper Eastern Shore
Soil moisture levels are all over the board. Some areas have been receiving rains while others have not. None of the region is too wet. Therefore, corn and early bean yield predictions also vary, but not disastrous. Corn will be 100-250 bu/acre plus. Early beans will be 40-80 bu/acre plus. Later maturing beans still have a long ways to go. Corn leaf diseases have been expanding/moving up the plant in the last few weeks. Soybean diseases have been minimal, but foliage feeding insects are increasing. Luckily most of the beans have plenty of foliage and can withstand some feeding. Trouble weeds, especially the glyphosate resistant weeds are starting to outgrow beans and showing their ugly heads(growing points). As with past months, there has been good quality hay harvested.—Jim Lewis, Caroline Co.
Lower Eastern Shore
Weather has been favorable and grain crops are looking good. Corn is around R3 reproductive stage. Full-season soybean is flowering. Deer are regularly observed grazing in soybean fields. Corn Earworm numbers are currently low. Herbicide-resistant weeds such as ragweed, marestail and Palmer amaranth are present and posing management challenges.—Sarah Hirsh, Somerset Co.
Southern Maryland
The story this month is squarely focused on moisture. Temperatures across the region are reaching into the 90’s with sporadic isolated storms hitting here and there. Crops are now showing moisture stress. The corn crop is past pollination and approaching dough stage on earliest plantings. We could really use another rain to help fill corn out, but it’s looking to be at least an average crop. Soybeans are setting pods, with full season beans at R3-R5. We have not seen many pest outbreaks in beans yet. We are on the lookout for spider mites with the hot dry conditions. Cool season grasses are going dormant in the hot dry weather.—Ben Beale, St. Mary’s Co.
Maria Cramer, Graduate Student | mec@umd.edu and Kelly Hamby, Extension Entomologist | kahamby@umd.edu University of Maryland, Department of Entomology
As soybean plants mature, tolerance for defoliating pests drops from about 30-35% during the vegetative stages to closer to 15-20% during the reproductive stages (flowering and pod fill). Any defoliation can look worrying, but it is hard to accurately measure defoliation. Most people tend to overestimate damage in three ways: overestimating the leaf area lost, not taking the full plant canopy into consideration, and not sampling the field randomly. Luckily, there are some great new tools to help you measure accurately and train your eye. Accurate measurement is the key to avoiding unnecessary treatments, saving you money, time, and preserving beneficials.
What defoliates soybean?
Grasshoppers tend to be concentrated on the edge of the field, especially near grasses or small grain fields1, and can cause jagged holes in leaves and sometimes clip pods (Fig. 1a).
Japanese beetle is an introduced pest that aggregates in large groups and skeletonizes leaves (Fig. 1b).
Bean leaf beetle is a native pest that can cause damage to seedlings, defoliate, and occasionally feeds on pods, but generally is not a problem on large plants unless other defoliators are abundant (Fig. 1c).
Mexican bean beetle occurs late in the season and feeds on the underside of leaves, causing a lacy appearance (Fig. 1d ).
Figure 1. a) Grasshopper, photo from Prairielands FS. b) Japanese beetle, photo from Prairielands FS. c) Bean leaf beetle (they can also be yellow or lack spots), photo by Wikimedia Commons. d) Mexican bean beetle, photo from University of Maryland Extension.
There are also caterpillars that can feed on soybean foliage.
Soybean looper is distinctly larger towards its tail-end, has two pairs of prolegs in the middle of its body, and moves in a “looping” fashion (curls its body into a hump while walking) (Fig. 2a).
Silver spotted skipper has thin stripes and a dark head-capsule, with a noticeable constriction (narrower) behind the head (Fig. 2b).
Green cloverworm looks similar to soybean looper and also moves in loops (notice hump forming in the image), but the two ends are the same size, and it has three pairs of prolegs in the middle of its body (gripping the stem in the image) (Fig. 2c).
Velvetbean caterpillar has four pairs of prolegs in the middle of their body and can also be identified by its violent thrashing when handled (Fig. 2d).
Figure 2. a) Soybean looper, photo by NCSU extension. b) Silver-spotted skipper, photo by Josh Em. c) Green cloverworm, photo by Daren Mueller. d) Velvetbean caterpillar, photo by Clemson University.
These pests make up the defoliating insect complex in soybeans, although they do not necessarily all occur together. However, if you must treat for them, make sure your insecticide works against the complex that is in your field.
When is defoliation a problem?
These insects become a problem when their defoliation exceeds treatment thresholds. Vegetative soybeans are tolerant of feeding, especially as they get larger, so until up to about two weeks prior to blooming this is around 30-35%. From about two weeks prior to blooming until pods fill (R7-R8) the treatment threshold is 15-20% defoliation. If defoliation exceeds these numbers at these times, yields can start declining, especially in drought conditions2. Pests that feed on pods (including some caterpillar species), have different thresholds, so it can be important to identify specific pests during sampling.
Sampling
To accurately determine percent defoliation, a thorough assessment of the field is necessary. Because many defoliators tend to congregate in the field, this means sampling a minimum of ten plants in four locations and averaging the results is needed for an accurate assessment. Figure 3, from the University of Nebraska Extension, outlines how to properly sample. Although this is a lot of sampling, it is important to eliminate bias and avoid overestimating damage. Nebraska Extension also has a work sheet3 to plug in your measurements for an average.
Figure. 3 Sampling soybean defoliation. Infographic by Justin McMehan, University of Nebraska.
If you see caterpillar pests in your field, you may also want to use sweep net sampling4 to determine which pests and how much pressure is present. The threshold for velvetbean caterpillar is ≥10 in 10 sweeps, and for soybean looper it is ≥15 in 10 sweeps. Corn earworms (Fig. 4.) which feed on terminals, flower clusters, and pods and can also be sampled using sweep nets. A dynamic threshold calculator5 has been developed for corn earworm in soybeans.
Figure 4. Corn earworm (also known as podworm).
New technology
Some good news is that even though it is hard to visually gauge defoliation, there are new tools you can use to be more accurate. One is the Crop Protection Network’s Soybean Defoliation Training6. With this tool you can use a slider to see what different levels of defoliation look like on a leaf. You can also test your skills by taking a quiz where you estimate defoliation. This is a great way to train your eye before you go out to sample.
Alternatively, if you have a smartphone, you can use a new app called “Leafbyte” to accurately assess defoliation7,8. With this app, you take pictures of leaves on a white background and the app calculates the percentage of leaf removed (Fig. 5).
Figure 5. Leafbyte app calculates the amount of leaf area missing from a leaf photographed against a white background.
Treatments
For many of these pests, avoiding broad-spectrum insecticides early in the season is likely to keep their populations in check. However, if defoliation has exceeded treatment threshold, you have several options; remember that less mature insects are easier to control. For most of these pests, pyrethroid products (e.g., Baythroid®, Warrior II®, Hero®) are reasonably effective and provide residual control. Soybean looper is an exception, because it has evolved resistance to pyrethroids, carbamates, and organophosphates (and other modes of action in the lower coastal plain areas of North Carolina), so it will not be controlled if these insecticides are used for other pests. Indoxacarb (e.g., Steward®), methoxyfenozide (e.g., Intrepid®), chlorantraniliprole (e.g., Coragen®, Prevathon®), spinosyns (e.g., Radiant®, Blackhawk®), and methoxyfenozide/spinetoram mixtures (e.g., Intrepid Edge®) can be effective9,10. Large grasshoppers require a higher rate of pyrethroid insecticides, while grasshopper nymphs (those without fully formed wings, Fig. 6) can be controlled using the insect growth regulator diflubenzuron (Dimilin®)11. When using insecticides, always consult and follow the label.
Figure 6. a) Grasshopper nymphs range from having no wings to having wing pads like the one pictured, but these do not cover the abdomen. Photo by Lyle J. Buss. b) Adult grasshoppers have wings that cover their abdomen. Photo by John L. Capinera.
Klubertanz TH, Pedigo LP, Carlson RE. Reliability of yield models of defoliated soybean based on leaf area index versus leaf area removed. J Econ Entomol. 1996;89(3):751-756. doi:10.1093/jee/89.3.751
Getman-Pickering ZL, Campbell A, Aflitto N, Grele A, Davis JK, Ugine TA. LeafByte: A mobile application that measures leaf area and herbivory quickly and accurately. Methods Ecol Evol. 2020;11(2):215-221. doi:10.1111/2041-210X.13340
Leafbyte app: https://zoegp.science/leafbyte
Cook DR, Crow W, Gore J, Threet M. Performance of selected insecticides against soybean looper in soybean, 2020. Arthropod Manag Tests. 2021;46(1):2021. doi:10.1093/amt/tsab020
Reisig D. Soybean looper thresholds and insecticide recommendation. NC State Extension.
Royer TA, Giles KL, Jeffcoat MD, Griffin J. Evaluation of Dimilin insecticide for control of a mixed-species grasshoppers using an RAAT application, 2000. Arthropod Manag Tests. 2001;26(1):10-11. doi:10.1093/amt/26.1.g54
Kelly Nichols, Agriculture Agent | kellyn@umd.edu University of Maryland Extension, Montgomery County
Japanese stiltgrass is an invasive grass that is typically seen in wooded areas. It likes shaded, wet areas and can easily take over the forest understory. Unfortunately, it can also creep into pastures and hay fields. The leaves of Japanese stiltgrass are wider and shorter than most of our common pasture grasses. There is also a distinctive silvery midvein that is slightly off-center from the middle of the leaf (Figure 1). Japanese stiltgrass also has a shallow root system, so it can be pulled out easily. For more information on how to identify stiltgrass, visit USDA’s National Invasive Species Information Center website.
Figure 1. Japanese stiltgrass.
The one (and only one) positive thing about this invasive is that it is an annual, so there’s no perennial root system to contend with. However, as an annual, stiltgrass spreads by seeds. Seedheads start to form in mid-September through October. Once they are visible but before they produce hard seed (Figure 2), mow the area to prevent the seeds from maturing and becoming viable. Stiltgrass will likely not have enough time to regrow and set more seeds before the first frost.
Figure 2. Japanese stiltgrass seed head emerging.
Herbicides are another option. A broad spectrum herbicide such as glyphosate, can be used to control stiltgrass; however, keep in mind that broad spectrum herbicides will injure or kill any plant that it touches. So, this would be an option for spot-spraying heavily infested areas.
Prowl H2O®, which contains the active ingredient pendimethalin, is labeled for applications on established grass that has at least 6 tillers. Prowl H2O is a pre-emergent herbicide, and must be applied before the stiltgrass emerges in order to suppress germination. Stiltgrass can germinate as early as when the soil temperature is about 50 °F, so Prowl H2O will need to be applied earlier than when we may be used to when controlling other summer annual weeds. While Prowl H2O is a good option, re-seeding restrictions of 10 months for pasture grasses and 6 months for alfalfa may make it a challenge for reseeding after the stiltgrass is gone. (Remember, Prowl H2O is a pre-emergent herbicide, so it will prevent grass and alfalfa seeds from germinating, too.) If Prowl H2O is used, manage the bare areas so that weeds cannot take over before re-seeding can be done.
Once a control method is implemented, re-seed bare areas so they are not left for stiltgrass and other weeds to fill back in. Following your nutrient management plan can also be helpful to provide the hay and pasture grasses the fertility they need to compete with the stiltgrass.
Amanda Grev, Forage & Pasture Management Specialist | agrev@umd.edu University of Maryland Extension
When it comes to something like mowing or clipping pastures, there are certainly two sides to the fence: those that think mowing or clipping pastures is just something that has to be done, and those that think it is a waste of time and fuel and offers little benefit. In truth, the reality is that both sides are right—the need to mow or clip is usually site and time specific and will depend on several factors. Sometimes the decision is easy, and sometimes the decision is less clear, so what are the arguments for or against mowing or clipping?
Eliminating Seed Heads. Mowing pastures is a strategy often used to eliminate seed heads in an effort to keep forages in a vegetative state and promote additional growth. As plants mature to a reproductive stage, they become less palatable to livestock and forage quality quickly decreases. Removing the stem and seed head through clipping or mowing encourages the plants to divert energy away from reproductive growth back to vegetative growth and the production of new leaf material, which will be higher in quality for livestock and will continue to capture sunlight and provide energy for the plant. Keeping plants in a vegetative state not only maximizes forage quality but also maintains a higher growth rate and stimulates tillering and root growth, promoting a denser stand.
One caution with this strategy—if eliminating seed heads is your main goal for mowing, be sure that there are enough seed heads present to validate this. Looking at a field from a “windshield” view often gives off the appearance that there are a lot more seed heads present than there really are, so be sure to go through the field and look at the seed head density from above. You may find that there are less seed heads present than you initially thought.
Promoting Even Grazing. This concept goes along with removing the seed heads and resetting the forages back to vegetative growth, as doing so can also promote a more even grazing distribution by livestock. Particularly if livestock have already been grazing selectively, mowing or clipping can eliminate forages that are heading and lower in quality and prevent the underutilized areas from becoming overly mature. By evening out the pasture, promoting uniform regrowth, and keeping the forage in a vegetative growth state, you can help minimize selection by livestock.
This is especially true for continuously grazed pasture where livestock have the ability to be more selective. For rotational grazing systems with frequent rotations, you may find this less necessary. With smaller paddocks and more frequent moves, livestock will already be less selective about what they eat and paddocks are more likely to be grazed evenly. Although this requires additional management, the return on this is less clipping, and less fuel and time spent doing so. So is the mowing worth it? In the long run, improving your management with rotation, adequate rest, and appropriate stocking rates will likely be more viable than continuously clipping underutilized areas.
Providing Weed Control. Mowing is often listed as a cheap, easy way to control weeds. Recognizing that there is a huge range in tolerance for weeds, particularly in pasture, most producers can probably still agree that certain weeds are more problematic than others and that some do have a negative impact on forage production and can lower the ability of the pasture to meet the nutritional needs of livestock. Mowing pastures is a form of mechanical weed control, and there are times when mowing or clipping can be useful, particularly if you have pastures with heavy weed pressure. In these cases, mowing can help eliminate competing vegetation and open up the canopy to favor the growth of desirable forages. Although mowing itself will not immediately control weeds or brush, it can prevent weeds from going to seed and help control their growth over time.
Of course the type of weeds present is an important consideration. Weed response to mowing will vary based on the time of clipping and the weed species present. Consider a pasture with an abundance of annual weeds; while mowing might help with their control in the short term, the presence of these weeds might be indicative of poor cover providing an opportunity for these species to fill in, in which case maintaining better cover would be a better focus for more success long term. For those harder-to-eliminate perennial weeds, although mowing may not be killing them outright, every time the plant is mowed it has to use additional energy for regrowth, draining its energy reserves and weakening the plant over time.
On the flip side, when considering mowing as a weed control strategy, be sure not to overlook the hidden costs. Factoring in time, along with fuel, maintenance, depreciation, and storage of equipment, most agricultural economists will place a minimum cost of $15 per acre on mowing. That’s really not all that cheap, especially when the results may be more temporary. It’s not that mowing can’t help control weeds, it’s that the number of mowings and the timeliness of each mowing are critical for long-term control. Effective control may require mowing two to three times each season over two or more years in order to fully prevent seed production and exhaust plant energy reserves. If we use the $15 per acre minimum, then we’ve spent $60 to $90 or more per acre for weed control.
In addition to the cost, recognize that mowing also removes some desired forage. Depending on the forage species and density, each inch of forage that is cut may remove 75 to 400 pounds of grazeable dry matter per acre. While mowing forage stands that have slowed or stopped growing can promote new, high-quality regrowth, repeated mowing over the season will reduce total available forage to some extent.
Controlling Pink Eye. Mowing or clipping can be a strategy to help control pink eye in cattle. While forage seed heads themselves do not necessarily cause pink eye, they can be an irritant and aggravate the condition. However, you may have a hard time justifying mowing for this reason unless you have an active pink eye problem. If pink eye is presently an issue, keeping seed heads under control using clipping or mowing could be justified to reduce possible eye irritations. However, that is usually only the case with high amounts of seed heads present, and controlling flies should be the first priority.
Maintaining Aesthetics. If aesthetics is your primary reason for mowing or clipping, the reality is you might be better off leaving it alone. Taller forages produce more live roots, which can provide some drought resilience. They can also help keep the canopy closed, shading out some weeds and keeping soil surface temperatures cooler and wetter, which can promote more growth from cool-season forages. They also have the added benefit of providing some wildlife habitat, especially for certain pollinator species. Pastures were never meant to look like mowed lawns, and keeping them as such is an added cost that has to be paid for by the enterprise.
All things considered, what is your primary reason for mowing? If your reason is to improve or maintain quality or to get on top of some persistent weed issues then you may find it useful. Mowing or clipping is one of the many tools we have for pasture management and it can have benefits. However, those benefits must be weighed against the costs that are associated with mowing pastures to determine if it is economical. In some cases, mowing will have a low return on investment, and you may be better off focusing on other things and reducing the time and money spent mowing.
