Selective, preemergence herbicides are typically used to control annual weedy grasses and some annual broadleaf weeds in lawns. Commonly available homeowner products contain one of the following active ingredients: pendimethalin, balan + trifluralin (trade name Team), balan, dithiopyr, corn gluten meal, and siduron (only one that can be used when reseeding). The herbicide prodiamine is available to commercial applicators but not available in the homeowner market, at least in the Twin Cities area. The herbicide isoxaben can be used to control certain broadleaf weeds preemergently in lawns but it too is not available for homeowner use. Always consult the product label as to whether or not the herbicide will control the targeted weed and that it is labeled for use on the lawn.
Unlike many of the other warm season annual grasses, longspine sandbur (Cenchrus longispinus) is difficult to control in lawns with premergent herbicides. While long-spined sandbur is not specifically mentioned on the dithiopyr label, it does mention sandburs (Cenchrus spp.) generally as weeds the product will control. It should also be noted that field sandbur (Cenchrus incertus), which is NOT found in this area, is sometimes listed on the labels of other products (e.g., pendimethalin [lawns], oryzalin [non-lawn areas]) as a weed controlled by those products. One should not necessarily assume that longspine sandbur will be controlled if the product lists only field sandbur on its label.
Selective, preemergence herbicides can also be used in shrub borders, annual and perennial flower beds and in groundcover areas. In some cases the active ingredients will be the same as those mentioned for use on lawns. However, additional herbicides include isoxaben, oxidiazon, trifluralin and oryzalin. Only trifluralin and oryzalin are available for homeowner use. Isoxaben and oxidiazon are not typically available in the Twin Cities homeowner market. Always consult the product label as to whether or not the herbicide will control the targeted weed and that it is labeled for use on/in the desired garden plants or landscape planting area.
Selective, postemergence broadleaf herbicides can be used to control these weeds in lawns. Commonly available homeowner products contain one or more of the following active ingredients: 2,4-D, 2,4-DP, MCPP, MCPA, dicamba, triclopyr, carfentrazone, sulfentrazone, quinclorac. Make sure that the products being used state on the product label that they are for lawn use.
In general, more effective control of white clover can be achieved with products containing MCPP and/or triclopyr. These can be found separately or in combination with many of the active ingredients mentioned for Strategy 4. Fall applications usually provide better results.
Control of birdsfoot trefoil will usually be more effective with combination products of selective, postemergence herbicides such as 2,4-D + MCPP + dicamba or MCPP + MCPA + dicamba + carfentrazone or triclopyr in combination with one or more of the active ingredients above. Apply herbicides in spring as new growth is developing or in early September to early October when temperatures cool and the plant is more actively growing.
Selective, postemergence control of mint family plants (e.g., creeping Charlie, henbit, heal-all) is usually more effective with products containing triclopyr, either by itself or in combination with one or more of the materials mentioned in Strategy 4. In has also been reported that control of these same mint family plants is rather poor when only 2,4-D is used. The use of the product Borax has also been reported. Click here for more information about its use in controlling Creeping Charlie.
A common homeowner available postemergence herbicide for selective control of warm season annual grasses is MSMA (monosodium methanearsonate). It can be purchased separately or in combination with selective broadleaf herbicides. This product should not be used when lawn grasses are under heat and drought stress as injury or even dieback of those lawn grasses may occur. Two other products with similar uses are DSMA (disodium methanearsonate) and CMA or CAMA (calcium acid methanearsonate) can also be found for homeowner use. The same cautions as for MSMA also apply to these two herbicides.
The postemergence herbicide quinclorac is also quite effective in controlling warm season annual grasses. For homeowners, it is only available in combination with other broadleaf postemergence herbicides. Another commonly available herbicide to the commercial lawn care industry but not homeowners is fenoxaprop (Trade name Acclaim Extra).
Other postemergence materials for controlling yellow nutsedge in lawns include halosulfuron and bentazon but they are only available to commercial lawn care providers.
Non-selective, postemergence herbicides can be used to control perennial grassy weeds such as quackgrass, tall fescue, and creeping bentgrass in home lawns as well as many different broadleaf weeds. The most common active ingredients for home use include glyphosate (e.g., Round-Up among many others) and glufosinate ammonium (e.g., Finale). Since both the weedy plants AND lawn grasses will be killed by these products, you will need to reseed or resod the treated areas. Typically that can occur in 10 to 14 days after treatment. However, be sure to follow product label directions exactly for use and application.
Some of the selective, postemergence broadleaf herbicide active ingredients contained in Strategy 4 may also be found in products for use in non-lawn areas; often at higher concentrations. Be very careful, when using these materials in and around desirable broadleaf plants such as garden flowers, wildflowers, trees and shrubs as they can cause serious injury and even death to those plants should they come in contact with the herbicide. Always explicitly follow product label directions for use.
Thistles can be controlled with selective herbicide applications of 2,4-D or triclopyr at the pre-flower bud stage of growth. May require multiple applications. Non-selective herbicides can also be used at that same stage. This too may require multiple applications. Fall treatment of the rosette (i.e., circular basal cluster of leaves) stage of growth with either of the selective herbicides mentioned or the non-selective herbicide glyphosate can also be done.
Non-selective, postemergence herbicides are most commonly used in non-lawn areas. Common postemergence, non-selective herbicide active ingredients for home use include glyphosate and glufosinate ammonium. As the term non-selective implies, these products will destroy all of the vegetation, grasses and broadleafs, that they contact. Therefore, be very careful, when using these materials in and around desirable broadleaf plants such as garden flowers, wildflowers, trees and shrubs as they can cause serious injury and even death to those plants should they come in contact with the herbicide. The herbicide Rodeo is the glyphosate product labeled for use in or near water areas. Always explicitly follow product label directions for use.
Sethoxydim and fluazifop-p-butyl are two homeowner available selective postemergence herbicides for taking grassy weeds out of broadleaf plantings such as flower beds, groundcovers or shrub borders. However, do not use them where there is potential to contact ornamental grasses as they can injure them as well. These two herbicides do not control broadleaf weeds.
Control of the woody vines Virginia creeper and wild grape are somewhat similar. Glyphosate applications are best applied from late August through late September but before a frost. If it is growing among other desirable plants, one will need to be very careful when treating these vines with glyphosate or any other broadleaf herbicide to avoid injuring or killing them. Where they are growing among desirable plants and the above mentioned controls would be too risky, these vines can be cut off near the soil line and the stumps treated with a combination of glyphosate or triclopyr or a combination of the two. These treatments can be performed from late summer all the way through late fall and generally provide good control come the following spring.
Several herbicide active ingredients are effective in poison ivy control. Products containing a combination of the selective broadleaf herbicides, 2,4-D, 2,4-DP, MCPP, MCPA, dicamba and triclopyr can effectively control poison ivy. However, repeated applications of the any regrowth will be necessary until the plant is finally killed. The non-selective herbicides glyphosate and glufosinate ammonium can also be used although glyphosate is moved through the plant more readily and usually results in quicker control. Even with these products, repeat applications will likely be needed.
Where poison ivy grows among desirable plants such as wild flowers, ferns, woody shrubs and trees, always be extremely careful with any herbicide used such that the product only contacts the poison ivy as other plants can easily be damaged or killed with these same products. Cut stump treatments with glyphosate and/or triclopyr can also be effective. Always read the product label for specific application directions. POISON IVY CAN CAUSE SEVERE ALLERIGIC REACTIONS IN PEOPLE AND ONE SHOULD ALWAYS BE WEARING PROTECTIVE CLOTHING SUCH THAT ANY HUMAN CONTACT WITH ANY PART OF THE POISON IVY PLANT CAN BE AVOIDED.
Cut stump treatments with the herbicides glyphosate, triclopyr or a combination of both are effective ways to prevent regrowth of either common or glossy buckthorn, or the exotic honeysuckle shrubs. The herbicide triclopyr can be applied to the lower stem area a foot or two above the soil line for control as well. These treatments can be performed from late summer all the way through late fall and generally provide good control come the following spring.
Small plants with foliage, under a couple of feet, can be treated with a variety of broadleaf weed killers such as those mentioned in Section III. For buckthorn, this is best done in early spring or late summer into early fall as these plants leaf out early and retain green foliage well into the fall period. Be very cautious when applying broadleaf weed killers in and around desirable plants located in the same general areas as the buckthorn or honeysuckles. They have the potential to injure or kill other broadleaf plants as well. For a more detailed discussion of buck thorn control click here.
Dodder is very difficult to control chemically and is really best accomplished with preemergence herbicides that kill the germinating dodder seedlings. Products such as pendimethalin, balan, trifluralin, prodiamine (available through commercial pestictide applicators only), and oryzalin are reported to be effective along with the preemergent herbicide dichlobenil. Preemergence herbicides would need to be applied by early to mid-May to be effective. The postemergent herbicide glyphosate has also been shown to be effective but it will damage or destroy the infested plant as well as the dodder. Broadleaf herbicides such as those mentioned in Section 11 have not been shown to be effective and, again, the infested plant can be damaged or killed with these products as well. Always explicitly follow product label directions for use.