North-Central Summary

Fall weed control in pastures and on rangeland would be a good investment this year, especially with recent weather extremes limiting management opportunities earlier in the year, says Katie Conklin, DuPont range and pasture specialist for North Dakota and South Dakota.

“In our area, the big three topping the fall weed control list are thistles, leafy spurge and absinthe wormwood due to new growth late in the season.”

“Moisture levels continue to vary in our region, with much of Colorado and western Kansas and Nebraska remaining very dry, while the eastern parts of those two states have had healthy amounts of rain this season,” adds Chris Bryan, DuPont range and pasture specialist for Nebraska, Kansas and Colorado.

“Each situation brings its own set of challenges when it comes to weed control, especially in the fall.”

South-Central Summary

Many parts of the region have received much-needed moisture this season, but most pastures and rangeland are still recovering from drought.

The damage to some ranch lands will require several years of recovery, says Gerald Hobson, DuPont range and pasture specialist for western Texas, southwestern Oklahoma and New Mexico.

“Making prudent pasture and rangeland management decisions now is more important than ever.”

A fall herbicide application can help control late-season germinating weeds such as broomweed and thistles, says Jack LeClair, DuPont range and pasture specialist for eastern Texas and Oklahoma. “It can also help you get the jump on winter weed control with pre-emergence herbicide activity.”

West Summary

Moisture has returned to many parts of the West this season, but rangeland affected by drought and wildfires is still in recovery.

Continuing to make good management decisions is critical for that recovery, notes Nevin DuPlessis, DuPont range and pasture specialist for Washington, Oregon, Idaho, Utah and Nevada.

“Ranchers are seeing new weed problems or heavier weed pressures from tough species. Dealing with them in the coming months will reduce competition and help grasses get a better start next spring.”

Several common noxious weeds are most effectively controlled with fall herbicide applications, adds Robby Brattain, DuPont range and pasture specialist for Montana and Wyoming. “If weeds such as Russian knapweed, whitetop, toadflax or thistles are expanding on your grazing acres, now is the time to control them.”

Jack LeClair
East Texas and Oklahoma

Several challenging late-summer and fall weed species include annual broomweed, thistles and sericea lespedeza.

The sooner you control these weeds, the less effect they’ll have on grass growth and yield next spring.

Fall is a good time to control several types of thistles, including musk and bull thistles.

A fall application of herbicide can deliver good root absorption by certain woody species, including dewberry.

The perennial legume sericea lespedeza is another difficult-to-control brush species. Mowing doesn’t work, and burning your pastures is the same as planting sericea lespedeza, since the fire scars the seeds, helping them germinate. An application of herbicide during the bloom stage is the best control option.

If you’ve had weed escapes in bermudagrass pastures, an application of herbicide made after you’ve cut hay or rotated cattle off the pasture can control summer annuals and perennials, specifically KR bluestem, which is more of a problem in southern Texas.

If you typically have more problems with winter grasses such as brome, ryegrass, little barley and wild oats, fall is a good time to scout for them so you can make an application now or later in the winter.

We’ve seen heavy grasshopper infestations this year and will likely have fall armyworms as well. If moth or worm counts are above treatment thresholds, growers should consider an application of an insect control with a long-lasting residual and no grazing or haying intervals.

After you’ve taken care of the weeds, it will be time to fertilize grasses. Use soil testing to ensure they have adequate potassium for strong root development to help desirable grasses outcompete weeds.

Matt McGowin
Louisiana, Mississippi, Arkansas, Tennessee, Kentucky, Alabama

While fall tends to be a busy time for most farmers and ranchers in the mid-South, it also offers the opportunity to control two key pasture pests: smutgrass and fall armyworms.

Smutgrass is one of the toughest weeds to control in coastal region pastures.

The key is to take action before weed densities increase.

With rainfall and incorporation, a well-timed application of herbicide is very effective on smutgrass in bermudagrass and bahiagrass.

Pastures treated at 4.5 pints per acre or less may be able to be grazed immediately or cut, dried and fed 38 days after application.

Fall armyworms feed on many forage crops but prefer lush bermudagrass. Because they can persist through October, it’s important to continue to scout pastures into the fall, especially after rain showers.

Scouting when armyworms are most active – early morning or late afternoon – will generate more accurate results.

If moth or worm counts are above treatment thresholds, an application of insect control with long-lasting residual and no grazing or haying intervals can provide effective control and maintain tonnage in the important last hay cutting.

Robby Brattain
Montana and Wyoming

Fall is the best time to control alyssums and cheatgrass and tackle noxious weeds that may have greened up from fall moisture.

Russian knapweed, whitetop, toadflax and thistles can be effectively controlled.

Invasive perennials yellow toadflax and Dalmatian toadflax start growing again in fall with a little moisture, even after setting seed.

Houndstongue and poison hemlock can be treated in the fall, providing some residual control into the next season.

Several alyssum species are also becoming more of a problem in our region, including yellow, desert and hoary alyssum, which is toxic to horses. They’re very aggressive and can choke out alfalfa fields if left unchecked or make inroads into rangeland.

With adequate moisture this season, the real impact could be seen next spring, when new grass seedlings are more likely to emerge and existing plants should become more vigorous.

Katie Conklin
North Dakota and South Dakota

Leafy spurge is a fairly common pasture menace, but some growers report seeing the creeping perennial in new areas this year.

If addressed early, infestations can be effectively controlled.

Absinthe wormwood has become more of a problem in the Dakotas over the past five to 10 years, usually invading disturbed areas of the pasture where cattle congregate, especially in dry soils.

Last year was a good year for the weed, which is easy to recognize due to its strong sage odor. As with leafy spurge, it’s easier to get good control of absinthe wormwood by treating it before it gets a foothold in your pastures.

Canada thistle did well in last season’s dry conditions, and few producers attempted to make herbicide applications last fall.

Control could be critical this year to keep things in check. The best time to make an application of herbicide on Canada thistle or musk thistle is after the first light frost but before the killing frost. Herbicide absorption and translocation is best when the application is made during the plant’s rosette stage.

Chris Bryan
Nebraska, Kansas and Colorado

Fall is a good time to control thistles, including musk thistle and Canada thistle.

Since musk thistle reproduces solely from seed, the key to successful control is to prevent seed production.

A well-timed application of herbicide when fall-emerged seedlings are in the rosette stage is most effective.

Canada thistle can also spread via roots, so herbicides offer the best control option, with a fall application providing the most consistent control.

Lady’s (milk) thistle has also started to show up in more rangeland and may merit control this fall.

Due to drought conditions and overgrazing, western ragweed has become increasingly competitive with grasses. The perennial produces new growth primarily from rootstocks and often has enough active growth in the fall to allow effective herbicide control.

Another weed that has become a challenge to control on grazing land is sericea lespedeza. Recently added to Nebraska’s noxious weed list, the perennial legume is difficult to control through mechanical means. An application of herbicide after flowering is one of the best control options.

Frank Jones
Florida, Georgia, South Carolina, North Carolina and southern Virginia

As the haying season winds down, growers have another chance to tackle invasive grasses in bermudagrass pastures.

Crabgrass, bahiagrass and johnsongrass can be season-long problems, but an application of herbicide made after the last cutting can knock down invasives.

Applications can be made after pasture grasses are dormant.

We have seen some benefit from a fall herbicide application that reduces spring weed populations. Controlling weeds also allows pasture grasses to make better use of fertilizers.

Many growers don’t think about applying an herbicide in the fall, but it can be an excellent investment. Not only does it help reduce weed populations, but it will increase the quality of your first hay cutting next season and help pasture grasses make better use of added nutrients.

Gerald Hobson
West Texas, southwestern Oklahoma and New Mexico

Keep in mind the three R’s – rest, rainfall and recovery – when making pasture management decisions.

A critical part of “rest” is adjusting cattle numbers to avoid overgrazing.

It also means controlling weeds and brush to allow desirable grasses to recover.

Fall is a good time to control problem weeds such as broom snakeweed in western Texas and sericea lespedeza in Oklahoma with herbicide.

Huisache is a problem brush species in southern Texas that can be controlled effectively. The aggressive KR bluestem also poses a threat to grass recovery in southern Texas.

Late fall is a good time to test soils and apply phosphate and potash to bermudagrass pastures. It’s also a good time to evaluate your management choices for the season, determine what worked and what didn’t, and make plans for next year.

Nevin DuPlessis
Washington, Oregon, Idaho, Utah and Nevada

Many acres of rangeland are still recovering from last year’s wildfires, and cheatgrass control is an ongoing challenge.

Fall offers an opportunity to get the upper hand on cheatgrass and medusahead.

Herbicide can be used to control those and other tough weeds on rangeland that is being restored and won’t be grazed for at least one year after application.

Fall is a good time to control weeds along fencelines and in areas where you plan to feed cattle this winter. For many brush species and Canada thistle, herbicides can provide effective suppression or control.

If you had weed problems in your pastures and rangeland this season, they won’t go away over the winter unless you take action this fall.

Fall armyworms have been a concern in grass pastures again this season. Because they can persist through October, continue to scout pastures into the fall, especially after rain showers. Scouting when armyworms are most active – early morning or late afternoon – will generate more accurate results.