Weeds

Forage Weeds: Fall Forgotten and Spring Startups

Alyssa Essman, OSU Extension State Specialist, Weed Science, Christine Gelley, OSU Extension Educator ANR, Noble County, Kyle Verhoff, OSU Extension Educator ANR, Defiance County

Spring means rapid forage growth, but it also means rapid weed growth. Due to the variability of spring weather, there are often only a few opportunities to control emerging summer annual weeds, winter annuals missed in the fall, and biennials that are small enough to effectively control. To manage weeds before they become a problem in forages, it is important to scout and plan accordingly. Forage is a broad category, and the spring weed control plan can look very different between species and operations. The problem weeds and whether control is necessary are going to be different between permanent pasture systems and alfalfa fields, and highly dependent on the consequences of specific weeds.

In established alfalfa, the decision for weed control of some winter annuals like henbit and field pennycress will depend on the severity of the weed presence, the age of the stand, and the end purpose of the forage. If the weed pressure is high, the stand is young, or the lower forage quality of the weeds interferes with the goal of producing dairy-quality hay, the weed control treatment may be worth the associated cost. In a grazing system, it may be more pertinent to control weeds in the spring to ensure weeds that aren’t grazed don’t go to seed. Numerous weeds can be a problem in forage systems. Reference the 2024 Weed Control Guide for specific recommendations following this general overview.

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Weed of the week – Common Pokeweed

Common Pokeweed (AKA – Pokeberry)

Family:  Pokeweed Family

Life cycle: Perennial

Description: A large, 3 to 10 ft tall, perennial weed with thick, reddish-purple branched stems and dark purple to black berries. All parts of the plant are poisonous to cattle, horses, swine, and humans, especially the roots.

Seedlings: Cotyledons 7-33 mm long, 6-11 mm wide, egg-shaped but pointed at the apex. Stems below the cotyledons (hypocotyls) are without hairs, succulent, and often purple-tinged. Young leaves alternate, egg-shaped but pointed at the apex, and without hairs. Cotyledons and young leaves are pale green in color, with reddish tinted petioles.

Roots: Large, white tap root up to 6 inches in diameter.

 

 

Stem: Branch from the root crown at the base of the plant, erect, large, smooth, purple-tinged.

Leaves: Alternate, 3 1/2-12 inches long, 1-4 inches wide, egg-shaped, petiolated, without hairs, and are smaller in size toward the top of the plant.

Flower: Individual flowers small (6 mm wide) with 5 white to pink-tinged sepals.

Fruit: A berry, 7-12 mm, green when immature, dark-purple to black when mature. Contain a dark red juice.

 

Special identifying characteristics: Large, tree-like plant with egg-shaped leaves, purple-tinged stems and dark purple berries.

Pokeweed Control in Corn and Soybeans

 

Blankets of Yellow Flowers

– Christine Gelley, Agriculture and Natural Resources Educator, Noble County OSU Extension

Fields of yellow flowers are abundant this year across the state as many annual crop farmers faced planting delays. Some pasture fields are covered in blankets of yellow too. The scenes are deceptively beautiful with their sunny appearance but may actually pose a deadly threat to livestock if the plant happens to be cressleaf groundsel, which is also known as butterweed. Cressleaf groundsel is another weed known to cause livestock poisonings in harvested or grazed forages.

Cressleaf groundsel is known to cause livestock poisonings.

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Kill Poison Hemlock Now

 

– Christine Gelley, Agriculture and Natural Resources Educator, Noble County OSU Extension

Poison hemlock is a concern in public right of ways, on the farm, and in the landscape!

Poison hemlock has already emerged in a vegetative state around Noble County and beyond. Soon it will be bolting and blooming on stalks 6-10 feet tall. All parts of the plant are toxic to all classes of livestock if consumed and is prevalent along roadsides, ditches, and crop field borders. It is a biennial weed that does not flower in the first year of growth but flowers in the second year. The earlier you can address poison hemlock with mowing and/or herbicide application, the better your control methods will be.

Poison hemlock is related to Queen Anne’s lace, but is much larger and taller, emerges earlier, and has purple spots on the stems. Another relative that is poisonous is wild parsnip, which looks similar to poison hemlock, but has yellow flowers. Giant hogweed is another relative of poison hemlock that is also toxic. All of these plants have umbel shaped clusters of flowers.

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Take Action Weed Management Webinars

By: Dr. Mark Loux, OSU

Given how messed up the whole herbicide supply and price thing is right now, it might be a good time to take advantage of free resources to improve your herbicide and weed management acumen. The USB Take Action program and university weed scientists are once again conducting a series of webinars to cover several key topics in weed management. Three webinars occur this month, and will be followed by the release of videos covering other pertinent weed-related subjects. January webinars include the following:

Value of Residuals in Herbicide-Resistant Weed Problems – Thursday, January 20, 11 am EST

Harvest Weed Seed Control Practices – Thursday, January 27, 11 am EST

Registration information can be found here.  Videos of the webinars will be made available following their broadcast.

Another great resource is the “War Against Weeds” podcast.  This podcast features guests with expertise in a variety of aspects of weed science, and discussions on integrated weed management, herbicide resistance, and other timely topics. The podcast is hosted by Sarah Lancaster, Kansas State Extension Weed Science Specialist, Mandy Bish, Extension Weed Scientist at the University of Missouri, and Joe Ikley, Extension Weed Scientist at North Dakota State.  Podcast episodes are available at https://waragainstweeds.libsyn.com/ and also on Spotify, iTunes, and Google Podcasts.

 

 

Cressleaf Groundsel in Hay

Source: Jason Hartschuh, CCA, Ted Wiseman, OSU Extension

Cressleaf Groundsel is in full flower currently in forage and unplanted fields across the state. While this is not a new weed prevalence has been increasing, causing concern for many livestock producers.

 

Toxicity

Cressleaf Groundsel is toxic to both cattle and horses. Cattle are 30-40 times more susceptible to poisoning than sheep or goats. Calves and younger cattle are more susceptible than older cattle, but it can be fatal at high enough doses to all age groups. Pyrrolizidine alkaloids are the principle toxin in these plants. It is known to cause liver disease in cattle, producing symptoms such as listlessness, decreased appetite, depression, anorexia, diarrhea, and photosensitization in extreme cases. It also appears that this species has been responsible for abortions in cattle, making control of butterweed a necessity. Cattle that consumed 4 to 8% of their body weight in the green plant over a few days developed acute liver necrosis and died within 1 to 2 days. Cattle that ingested 0.15% of their body weight (fresh weight) of a species in the same genus as butterweed for a minimum of 20 days resulted in 100% mortality. This comparative ratio equates to a 20-day cumulative dose of 2% of an animal’s body weight of dry plants (Knight and Walter 2001). Most beef cattle will consume 2-2.5% of their body weight in dry matter per day. Since these toxins are cumulative when hay is over 5% Cressleaf Groundsel dry matter weight, enough can be consumed within 20 days to cause mortality.

Cressleaf Groundsel

While toxicity decreases in some plants as they dry, that is not the case with Cressleaf Groundsel. These toxins are not decreased if the plants are dried and baled. Ensilaging will decrease the concentration of toxin but not eliminate them. Producers with high concentrations of Cressleaf Groundsel maybe forced to bale first cutting and throw it away so that livestock are not poisoned. Areas of sparse concentration may be baled and fed cautiously, ideally alongside hay that is free from poisonous weeds. Cattle may sort the weeds out. A new bale should be fed before the only thing left in the feeder is weeds. In grazing situations, cattle will usually not eat poisonous plants as long as they have access to other quality forages. Be cautious anytime drought conditions decrease forage stands.

Biology and Identification

Cressleaf groundsel reproduces only from seeds and emerges as a rosette in the fall, then bolts, flowers, and goes to seed in the spring.  Bolting stems are hairless, hollow, grooved, and can reach heights of three feet with inflorescences that have six to twelve yellow ray flowers.  The flowers are like other species in the Aster family, with ray (outside) and disk (center) petals.  The outer ray will normally consist of 5 to 15 petals that are bright yellow, and the inner disk will be a more golden yellow in color.  Plants will eventually produce seeds that resemble those of dandelions.  The seeds are small with a reddish to brown tint and have a feathery pappus that makes them easily carried by the wind.

Control

Cressleaf groundsel normally does not regrow after the first cutting of hay; however, our goal should be to prevent it from becoming established in the field. Take note of fields with Cressleaf Groundsel in them or nearby for increased scouting and control measures next year.  Effective chemical control is when the plants are still in the rosette growth stage in late fall or early spring.  Herbicides such as 2,4-D provide good control when applied at the correct growth stage.  Larger plants may require additional herbicides such as dicamba.  Products that can be used to control this weed and others can be found in the 2020 Weed Control Guide for Ohio, Indiana, and Illinois.  One caution using these broadleaf herbicides is that they also damage legumes such as alfalfa and clovers in pastures and hayfields.  For additional information on identifying weeds go to https://cpb-us-w2.wpmucdn.com/u.osu.edu/dist/7/3461/files/2014/04/Cressleaf_groundsel_article_-_p-zna9t9.pdf

Control of Multiflora Rose in Pastures

– Dean Kreager, Licking County Agriculture and Natural Resources Educator (originally published in Farm and Dairy)

There is one pasture project that never seems to go away. That is controlling the multiflora rose. The plant was first introduced into the United States in 1866 to be used as a rootstock for grafting roses. About 70 years later the U.S. Soil Conservation Service promoted the use of multiflora rose as a “living fence” and a means of erosion control. The adaptability of this plant allowed it to get out of control. Over the years this plant has made the list of noxious weeds in many states and is taking over many pastures in this part of the country. The battle to gain control is difficult and maintenance is continual.

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Wet Years have Favored Weeds

Melissa Bravo, agronomic and livestock management consultant
Previously published in Hay & Forage Grower: April 21, 2020)

 

Here we go again. Another mild winter of heave and thaw with little snow cover to protect the shallow roots and crowns of improved forage crops.

Without that snow barrier, species such as alfalfa and timothy — the most susceptible of our non-native forages — are subject to winter injury, which thins stands. This leaves less competition for weeds to establish and flourish.

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