Managing Small Pastures to Reduce Weed Problems
Bob Parker
Revised October 24, 2008
Serious weed problems in pastures are a symptom of a problem with the crop or site. Problems can include grazing methods, fertilization, forage species, and water management.
In many situations, land used for grazing livestock will not warrant the major expense required for herbicides or other methods to control weeds. Thus it is usually more appropriate to look for ways to manage the forage and the site to prevent or reduce weed problems. In many cases, changing the grazing methods, fertilization, forage species, and water management will change the competitive balance in favor of the forage rather than the weeds.
Healthy and well-established forage plants have a good chance to resist weed invasions. Therefore, manage desirable forage species to make them as competitive as possible with weeds. Sites such as gates, water troughs, feed bunks, bedding grounds, roadways, and fence lines should be the first to receive attention because forage plants are sparse there and the soil is disturbed. Weeds often first become established in these spots; then, it is much easier for them to move out to grazing land. It is not practical to completely stop disturbing the soil, but reseeding a competitive grass can make the sites much less inviting to weed invasion. If it is not practical or economical to overseed an entire pasture, consider seeding livestock trails and reseeding both sides of roadways since this is where weeds likely show up first.
Pastures can be made more competitive against weeds by doing whatever is reasonable to promote the forage. This is crop management, not weed management. Controlling weeds does not necessarily mean an increase in forage yield. As a rule, every unit of weeds produced reduces forage by an equivalent amount. If available resources are used to make the crop grow better, a yield increase can be expected and the impact of weeds should be less. It is important that the forage species and variety be carefully selected for the site and the objectives. Then fertility, soil pH, irrigation or drainage, grazing management, mowing, and periodic overseeding all have potential to influence crop growth and ability to compete with weeds.
When forage deteriorates to the point that corrective measures must be taken, the question is how to best correct the situation. If tillage is feasible, it is tempting to start over by plowing or disking to prepare a new seedbed. This may be the best alternative, but more often it exposes a lot of new weed seeds to an environment that favors their germination. The land is out of production for several months, and nothing has been done to prevent deterioration again. Increased soil erosion and the relatively high cost are additional disadvantages of compete renovation.
It may be better to simply overseed the pasture by the most suitable method. Several types of no-till planters and techniques may be suitable. If the seed is simply spread on the soil surface, it will help to irrigate, or to run livestock over the field for a few days, or to harrow the field to move the seed into contact with the soil. Broadcast seeding spreads the seed over the entire area, which should be more competitive with the weeds than drilling in rows. No-till planting has the obvious advantages of not taking the field out of production for a long period, and there is little soil disturbance to expose new weed seeds to conditions that favor their germination. Extra seed is recommended when using the broadcast method.
In areas inaccessible to machinery, it may be appropriate to feed seeds of desirable species to the livestock so that the seed will be planted, after passing through the animals. Certain grasses and most small-seeded legumes remain viable after going through an animal’s digestive system.
There are times when direct action on weeds is advisable.
1. Weeds that are new to a farm and few in number should be controlled with a shovel, an herbicide, or another appropriate method before they become established.
2. Poisonous plants can cause unacceptable livestock losses. Implement control programs in grazing areas that are small enough and accessible. Fencing might be appropriate in serious cases, but herbicides or shovels are good tools if plants are widespread and relatively few. Poisonous plants frequently are the first to appear in spring. Delay introducing livestock into these areas until adequate forage is available, and then do not overgraze.
3. Certain perennial weeds—such as leafy spurge, field bindweed, and quackgrass—cannot be discouraged by competition from vigorous forage plants. Herbicides, physical removal, or tillage are common methods, but grazing different animals such as goats or sheep may be effective.
4. If weeds have become so dense and the forage species so thin that the site is unprofitable, using herbicides or tillage may be the best option. This should be done only when necessary.
In summary, direct management and resources to promote growth of forage species so they will be more able to compete with weeds. This concept is helpful in correcting certain weed problems and in slowing or preventing invasion of new weeds. Careful use of herbicides can be a useful tool for forage management. Livestock management follows closely behind management of the forage sites in overall importance. The best chemical for forage production is probably fertilizer.
When herbicides are called for, one of the problems is being able to buy products in the small quantities needed. Do not buy more product than needed for the current year, or storage may become a problem.
SMALL PASTURES
•  2,4-D (several products)
Rate  0.7 to 2 lb ae/A, depending on weed species and size
Time  Depends on target weeds. Apply to grass pastures when annual and biennial broadleaf weeds are small and actively growing and established perennials are at bud stage, unless indicated otherwise on the label.
Remarks  Controls many broadleaf weeds. The smaller the annual weeds, the easier they are to control. Spray biennial species in the seedling to rosette stage, before flower stalks are apparent. Spray perennial weeds while still seedlings (coming from seed), or wait until bud stage of growth.
Caution  Do not allow drift to desirable vegetation. Do not apply to newly seeded areas until grass is well established. Many forbs (desirable broadleaf plants) can be seriously injured or killed. Do not graze lactating dairy cattle in treated areas for 7 days after application. Preharvest interval is 30 days for hay. Do not permit animals being finished for slaughter to graze treated fields within 3 days of slaughter.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  MCPA (several products)
Rate  1 to 2 lb ae/A
Time  Apply to annual broadleaf weeds when small and actively growing. Spray perennials in early-bud to full-bloom stage and during regrowth in fall.
Remarks  Controls certain annual broadleaf and perennial weeds in grass pastures.
Caution  Do not graze dairy animals or meat animals intended for slaughter for 7 days after treatment. Preharvest interval is 21 days for hay. Do not use this treatment if alfalfa is present and desired. Do not use if temporary injury to clovers cannot be tolerated. Do not use on newly seeded areas until grass is well established. Do not use from early boot to milk stage if grass seed production is desired.
Site of action  Group 4: synthetic auxin
Chemical family  Phenoxy acetic acid
•  triclopyr (Garlon 3A) 
Rate  0.75 to 2 lb ae/A (1 quart to 0.66 gal/A product)
Time  Apply to grass pastures when broadleaf weeds and woody plants are actively growing.
Remarks  Adjust rate for type of vegetation to be controlled. Controls both emerged herbaceous and woody broadleaf plants. To control biennial thistles or other biennial species, apply before flower stalks appear. Add an approved nonionic surfactant to the spray mix.
Caution  Do not allow drift to desirable vegetation. Many forbs (desirable broadleaf plants) can be seriously injured or killed. Do not allow grazing or harvest green forage for lactating dairy animals from treated areas during the same growing season after application. Withdraw livestock from grazing treated grass at least 3 days before slaughter during the season of application. Preharvest interval is 14 days for hay.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  triclopyr + 2,4-D (Crossbow)
Rate  1% to 1.5% solution for spot treatments or up to 1 gal/A, depending on target weeds
Time  Apply to grass pastures when broadleaf weeds are actively growing.
Remarks  May not be applied to forage that is to be cut and sold for commercial purposes. Controls many broadleaf weeds. The smaller the annual weeds, the easier they are to control. Spray biennial weeds in the seedling to rosette stage, before flower stalks are apparent. This herbicide mixture is very effective on a number of woody species.
Caution  Do not allow drift to desirable vegetation. Do not apply to newly seeded areas until grass is well established. Many forbs (desirable broadleaf plants) can be seriously injured or killed. Note restrictions on label, particularly for grazing lactating dairy cattle and for overseeding or reseeding.
Site of action  (both) Group 4: synthetic auxin
Chemical family  (triclopyr) pyridine; (2,4-D) phenoxy acetic acid
•  triclopyr + clopyralid (Redeem R&P)
Rate  1.5 to 4 pints/A, depending on species, size, and stage of growth of target weed
Time  Apply to permanent grass pastures when broadleaf weeds are actively growing.
Remarks  Controls many herbaceous broadleaf weeds. Add a nonionic surfactant at surfactant manufacturer’s recommended rate. Apply in at least 10 gal/A water by ground. The smaller the annual weeds, the easier they are to control. Spray biennial species in the seedling to rosette stage, before flower stalks are apparent.
Caution  Do not exceed 4 pints/A per year. Do not allow drift to desirable vegetation. Avoid application under completely calm conditions which may be conducive to air inversions. Do not apply to newly seeded areas until grass is well established. Injures or kills forbs and other broadleaf  vegetation. Do not graze or harvest green forage for lactating dairy animals from treated area for 14 days or harvest for dry hay until the next growing season. No grazing restrictions for other livestock; however, there is a 7-day restriction for harvesting dry hay. Withdraw slaughter animals from treated area 3 days before slaughter. Do not use hay or straw or manure for composting or mulching. Note label restrictions on overseeding or reseeding.
Site of action  (both) Group 4: synthetic auxin
Chemical family  (both) pyridine
•  clopyralid + 2,4-D (Curtail)
Rate  2 to 4 quarts/A
Time  Apply to grass pastures when broadleaf weeds are actively growing.
Remarks  Controls many broadleaf weeds. Application rate depends on weeds to be controlled and density of the infestation. The smaller the annual weeds, the easier they are to control. Spray biennial species in the seedling to rosette stage and before flower stalks become apparent.
Caution  Do not allow drift onto desirable vegetation. Do not apply to newly seeded areas until grass is well established. Many forbs (desirable broadleaf plants, particularly legumes) can be seriously injured or killed. Do not graze lactating dairy cattle in treated areas for 14 days after application. Do not cut for hay within 30 days of application. Wait at least 2 wk after application to graze animals scheduled for slaughter in 7 days or less. Do not use hay or straw from treated areas for composting or mulching. Note label restrictions on overseeding or reseeding.
Site of action  (both) Group 4: synthetic auxin
Chemical family  (clopyralid) pyridine; (2,4-D) phenoxy acetic acid
•  aminopyralid (Milestone)
Rate  0.75 to 1.75 oz ae/A (3 to 7 fl oz/A)
Time  Apply to actively growing weeds. Consult label for specific weeds.
Remarks  A nonionic surfactant at 1 to 2 quarts/100 gal of spray enhances control under adverse environmental conditions. Controls several broadleaf weeds. Application rate depends on weed species and stage of growth. There are no restrictions on grazing or hay harvest.
Caution  Do not let spray drift onto desirable vegetation. Many forbs (desirable broadleaf plants) can be seriously injured or killed. Do not transfer grazing animals from treated areas where sensitive broadleaf crops occur without first allowing 3 days of grazing on an untreated pasture. Do not exceed 7 fl oz/A Milestone per year.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  fluroxypyr (Starane)
Rate  0.094 to 0.125 lb ae/A (0.5 to 0.66 pint/A)
Time  Apply to established grasses when broadleaf weeds are actively growing before they are 8 inches high. New grass plantings may be treated at the two-true-leaf stage of growth but before early boot.
Remarks  Refer to label for tolerant grasses. A second application may be made at least 14 days after the first. Only weeds emerged at the time of application will be controlled. Use the lower rate on broadleaf weeds less than 4 inches tall. There are no grazing restrictions for lactating or nonlactating dairy animals.
Caution  Do not exceed 0.166 ae/A (1.33 pints/A) per growing season. Preharvest interval is 7 days for hay or silage. Remove meat animals from treated forage at least 2 days before slaughter.
Site of action  Group 4: synthetic auxin
Chemical family  Pyridine
•  dicamba + 2,4-D (Weedmaster, Pasturemaster, or Latigo)
Rate  0.5 to 4 pints/A Weedmaster or Pasturemaster, or 0.33 to 2.5 pints/A Latigo, depending on weed species and size at application
Time  Depends on target weeds; see label. In general, apply to grass pastures when annual and biennial broadleaf weeds are small and actively growing and established perennials are at bud stage.
Remarks  Controls broadleaf weeds. The smaller the annual weeds, the easier they are to control. Spray biennial species in the seedling to rosette stage, before flower stalks are apparent. Unless label indicates otherwise, spray perennial weeds while still seedlings (coming from seed), or wait until bud stage of growth.
Caution  Do not allow drift to desirable vegetation. Do not apply to newly seeded areas until grass is well established. Many forbs (desirable broadleaf plants) can be seriously injured or killed. Do not graze lactating dairy cattle in treated areas for 7 days after application. Do not cut for hay for lactating dairy animals within 37 days of application. Do not permit animals being finished for slaughter to graze treated fields within 30 days of slaughter. Note label restrictions on overseeding or reseeding.
Site of action  (both) Group 4: synthetic auxin
Chemical family  (dicamba) benzoic acid; (2,4-D) phenoxy acetic acid
•  metsulfuron (Escort and others)
Rate  use 0.3 to 2 oz ai/A (0.5 to 3.3 oz/A) Escort
Time  Apply to actively growing weeds.
Remarks  Consult labels, which differ significantly. Information for Escort comes from a Section 2(ee) recommendation for pastures. Controls a wide range of broadleaf weeds. For best results, use a nonionic or silicone surfactant. No grazing restrictions for any livestock, including lactating animals, with application rates of 1 oz ai/A (1.67 oz/A) or less. Note restrictions on timothy, fescue , and ryegrass pastures. Note recropping intervals.
Caution  Do not allow drift to desirable vegetation. Injures or kills desirable forbs.
Site of action  Group 2: acetolactate synthase (ALS) inhibitor
Chemical family  Sulfonylurea
•  glyphosate (several products)
Rate  Consult label. Several concentrations of glyphosate are available.
Time  Depends on weed or brush species to be controlled. Annual weeds are best controlled when small and actively growing. Apply to perennial weeds at or beyond full flower or in late summer or fall after seed forms but before a killing frost.
Remarks  Controls susceptible grass and broadleaf plants including many desirable grasses and forbs. Use as a spot treatment, treating up to 10% of any area. Repeat applications can be made in the same area at 30-day intervals. Glyphosate is nonselective and may control all vegetation present, so consider reseeding the areas treated.
Caution  Will kill forage plants on contact; do not allow drift onto desirable vegetation. Remove livestock before applying and do not graze or harvest for 14 days after application. Do not exceed 6 lb ae/A or 8 lb ai/A per year.
Site of action  Group 9: inhibits EPSP synthase
Chemical family  None generally accepted