Weed & Pest
Logan researchers blend ag, biomedical research in cleft palate studyWritten by Emilee Gibb
Laramie – “While our mission is focused on the livestock industry, here was an opportunity where we were able to take our agricultural research that had been done, move it into the biomedical side and collaborate with plastic surgeons,” commented United States Department of Agriculture-Agricultural Research Service (USDA-ARS) Poisonous Plant Research Laboratory Supervisory Research Animal Scientist Kip Panter about the facility’s research with cleft palate repair.
Prior to their annual meeting, Wyoming Farm Bureau hosted a symposium for producers on Nov. 2, where faculty from the research facility in Logan, Utah presented some of their current research findings and projects.
One manifestation of crooked calf syndrome is a cleft palate, explained Panter.
“Sometimes producers will get cleft palate and no other symptoms in these calves,” he said. “The only way they would recognize it is, when the calf nurses, milk will come out of its nose because the esophagus and the trachea are not separated.”
The clinical signs observed with crooked calf syndrome depend on the day of gestation that the pregnant animal is intoxicated.
“The susceptible period of pregnancy for this lupine induced crooked calf disease begins 40 days. This is when the embryo first starts to move,” continued Panter.
He noted that the animal develops a cleft palate because the toxin in the plant moves across the placenta and inhibits the embryo from moving.
“It’s essential that this embryo start to move to avoid a cleft palate because it allows the tongue to drop out of the roof of the mouth so the palate can close and come together, which ends the embryonic period and starts the fetal development,” stressed Panter.
“We published a paper in 1992 describing the cleft palate in the goat model and the mechanism,” said Panter.
Their research attracted the interest of Jeff Weinzweig, head of plastic and reconstructive surgery for Laheu Medical Clinic in Boston, Mass., who was researching cleft palate in children at the time.
“He read our article and called and said, ‘Is there any chance that you guys would collaborate with us to try and find a model that we can study cleft palate in children to try and find an improved treatment in children?’” said Panter.
The researchers had enough information by that time to produce a cleft palate in the goat models without other birth defects.
With prior research, Weinzweig determined that fetal intervention by a certain period in gestation would allow the fetus to heal completely.
“If we can do the surgery as a fetus before day 100 of gestation, the fetus has the ability to heal without scar tissue formation,” explained Panter. “He wanted to give that a try, so we said okay.”
The equivalent time period of gestation in fetal goats was selected for the study.
“We selected day 85 of gestation. We were right at the beginning of the third trimester,” he continued.
Conventional cleft palate surgery, like what is typically performed on six-month-old children, was done on the fetal goats.
“It worked,” proclaimed Panter. “The baby goats were born with an absolutely normal palate, and we did a whole bunch of research with that after they were born.”
The research team has been working on the collaborative project for 10 years, and the project is still in progress.
“It’s not done yet because the surgery has not been approved by Food and Drug Administration to be done in people yet. It’s still at the animal phase,” said Panter.
Current treatments for children with cleft palate or cleft lip are extremely costly, both financially and time-wise, explained Panter.
“Right now, the cost of intervention in a child is between $700,000 and $1 million per child by the time the palate closure is done at three to six months of age, and they go through 12 to 15 major surgeries in their lifetime before they become adolescents and their facial structure quits growing,” he continued.
However, the experimental surgery the group has tested would dramatically reduce the number of surgeries and potential complication.
“Fetal intervention has the potential to repair that in utero and the children would totally avoid these surgeries and the complications that come after,” concluded Panter. “That’s the goal.”
Toxic plants are still problematic in late summer, early fallWritten by Emilee Gibb
Often overlooked and considered simply a problem in the spring, livestock producers should be aware of toxic plants in the late summer and early fall, says University of Wyoming (UW) Agriculture and Horticulture Extension Educator Brian Sebade.
“In the spring, we have things like larkspur that causes pretty sudden death for a lot of our cattle,” explains Sebade, “A lot of the fall plants have symptoms that might not pop up right away or livestock just look like they’re not doing quite as well.”
Many factors can attribute to animals being more prone to eat toxic plants in the fall, says Sebade.
He notes that oftentimes, toxic plants are the only plants that are still green, making them look more desirable to animals.
“Most of the time, we have animals that are really good at picking at stuff around the toxic plants, but sometimes, if it’s the only green thing around, they’re more willing to try it out,” explains Sebade.
Toxic plants can also be a concern if a producer is moving animals to an unfamiliar pasture or if producers purchase livestock from a different area.
“If a rancher is moving animals from a pasture that they’re familiar with to a pasture that they’re not used to – or just animals that the producer has brought in from a completely different area and moved them in – sometimes producers can have some issues. If livestock don’t know what the toxic plant is, they might try it out,” says Sebade.
In some cases, moving animals quickly through an area can result in intoxications as the animals only graze on the toxic plants.
“Moving through, they’ll chomp on it because they’re hungry. Then, they won’t eat anything else, and they get a high dosage,” says Sebade. “Most of these are toxic, but as long as they eat other things, they’ll likely be okay. Toxicity is based on the animal's bodyweight.”
Sebade suggests having adequate water and minerals available to animals to self-regulate their needs. Good grazing management is also crucial in reducing the incidence of intoxications.
“Try to move things around so animals aren’t always stuck at the water even though that’s a little bit tougher in August and September because it’s hot and dry,” continues Sebade.
The species that producers should be conscious of varies depending on the moisture of the site.
In wet areas that have moisture present in the top layer of soil and in the subsoil, Sebade’s top concerns are water hemlock, arrow grass and horsetail.
“Water hemlock is native to Wyoming, actually, and there’s poison hemlock, which is introduced. We actually had a lot of water hemlock that was along a lot of our riparian areas,” says Sebade. “Again, that’s kind of green, and it can kind of get mixed in with other palatable stuff.”
In soils with subsoil moisture that does not reach the surface, Sebade recommends producers be aware of hounds tongue, poison hemlock, hemp dogbane, chokecherry and Russian knapweed.
Sebade explains that chokecherry is not normally extremely toxic, but stress can increase the concentration of toxins in the plant.
“Most of the time it’s not a big deal, but if plants get damaged or they’re drought stressed, they tend to accumulate more of the toxin. It’s kind of like grapes where if we stress the plant out, we get more sugars in the grape. That’s what happens with chokecherry,” he says.
Producers should be conscious of bracken fern, tall larkspur and orange sneezeweed in higher elevation sites with some subsoil moisture, he says.
Toxic plants that favor dry or upland sites with little to no moisture in the subsoil are greasewood, halogeton and nightshades.
“Some of our upland sites might have halogeton, which can sometimes be pretty toxic. It’s greener later in the year making it look more palatable,” explains Sebade.
Spring versus fall
The plant species that are present during the fall are different than in the spring, says Sebade. As such, clinical manifestation of intoxication can present differently.
“The signs of many of the spring plants are going to be a little bit different than what we might have in the fall,” he says.
The type of toxin in the plant is the primary factor in how the plant will affect the animal. Most of the spring toxic plants, as well as some fall plants contain a more potent toxin.
“We have cyanide-type poisoning with something like chokecherry, poison hemlock or water hemlock. That’s a pretty quick deal,” says Sebade.
Alternatively, many fall toxic plants contain a less severe toxin, comments Sebade.
“Hounds tongue, on the other hand, builds up over time, and sometimes the symptoms don’t pop up right away,” he notes.
In either season, Sebade notes that intoxication is not considered a herd disease but rather affects individuals of herd.
“It gets a little difficult, and that’s probably why toxic plants are just kind of a pain. They don’t ever kill an entire herd. It’s usually just a few animals and sometimes the livestock just just look kind of stressed out,” concludes Sebade.
Concerns arise over herbicide resistant kochiaWritten by Natasha Wheeler
“I think it’s important for people to be aware that glyphosate resistance has been confirmed so that we can take proper management action before it gets worse,” notes University of Wyoming Extension Educator Caitlin Youngquist.
Recently, a kochia plant was confirmed to have resistance to glyphosate – the active ingredient in Roundup and other herbicides.
“It was brought to my attention through Extension. I was able to coordinate with growers, the local Weed and Pest, the University of Wyoming (UW) research station and a weed specialist in Laramie,” Younquist explains.
A rapid-response bulletin was released, warning growers, homeowners and landowners to be on the lookout for additional cases. The announcement also included suggestions for herbicide alternatives, based on the crop or land being managed.
“Herbicide stewardship is very important for preventing further spread of herbicide resistance,” Youngquist says.
If a herbicide-resistant weed is suspected, it should be destroyed, according to Gustavo Sbatella, assistant professor of irrigated crop and weed management at the Powell Research and Extension Center.
“Do not let it go to flower or seed,” Sbatella states.
The next step is to plan for herbicide rotation, changing the mode of action for controlling kochia weeds.
As an example, Sbatella explains, “If a farmer planted glyphosate-resistant sugarbeets and followed that with glyphosate-resistant corn, there is a possibility that the only herbicide that has been used in a two-year period is glyphosate. That puts a lot of selection pressure on any weed species, especially kochia.”
If those weeds begin to develop resistance, they may not be eliminated after herbicide treatments.
“If we have sprayed an area for any weed, and we notice that most of the plants where we have sprayed are dead or dying, but a few individuals are still thriving, that is a good indicator that we might have resistance there,” Youngquist notes.
“In the early stages of resistance, when we walk in the field, we are going to find some plants that are dying and some plants that are not. We will have different degrees after we spray in terms of plants that will die or survive,” comment Sbatella.
After other factors have been eliminated, such as spots that may have been skipped during herbicide application or tools that are not properly calibrated for even and accurate treatment, surviving plants may be an early indicator that alternate control methods are necessary.
“It’s important to be careful with the edges of our spray pattern,” Youngquist advises.
Weeds along the perimeter of herbicide treatment may come into contact with the herbicide but not with a strong enough dose to be eliminated.
“Watch those areas where resistance can develop,” Youngquist suggests.
These areas also include ditches, roadsides, rights-of-way and other areas that have been repeatedly sprayed with the same herbicide, such as glyphosate.
“Kochia is an annual weed, and it is very common in much of the western U.S., including Wyoming,” Sbatella adds.
Kochia seeds spread very efficiently, and the plants are drought resistant and easily adapt to alkaline soils.
“It is one of the many tumbleweeds that we have here in Wyoming. It is probably one of the most common, along with Russian thistle,” he continues.
It is also one of the first weeds of the season to germinate. This time of year, the plants typically flower and produce large quantities of yellow pollen.
“They don’t have any flashy flowers,” Sbatella explains. “They are similar to ragweed in terms of how inconspicuous they are.”
Originally, kochia plants were introduced to the United States as ornamental plants, and they established easily in the western landscape.
“Along with downy brome, it is probably one of the worst weeds in the western U.S.,” mentions Sbatella.
Sugarbeet farmers in particular struggle with kochia infestations in their fields.
“With sugarbeets, we don’t have many herbicides that will effectively control kochia. We also don’t have as many modes of action as we do with other crops,” Sbatella explains.
When glyphosate-tolerant crops were introduced, kochia control improved dramatically.
“But, if we keep repeating the same treatments, with time it might lead to the development of herbicide resistance. That is probably one of the things we are seeing here,” he adds.
If resistance is suspected, Extension or local Weed and Pest agents can be contacted for assistance.
“Contact the local Extension office,” suggests Youngquist. “If the plant is resistant, remove it by any means necessary, such as pulling them by hand, mowing or spraying with alternative herbicides.”
Weed management experts in Wyoming are taking action and looking for solutions to control kochia.
“There is more to do, and it will require working closely with growers, landowners and right-of-way managers, such as railroad, county and city staff, to carefully manage how we spray and how we use herbicides for kochia and other weeds,” Youngquist says.
Poisonous plants can affect horses, other livestock through introduction of toxic chemicalsWritten by Gayle Smith
Good pasture management can go a long way in preventing horses from becoming poisoned by toxic plants.
“Through good pasture management, recognizing toxic plants and understanding the effects of toxins on animals, plant poisoning can be largely avoided,” according to Tony Knight, who works with the College of Veterinary Medicine at Colorado State University (CSU).
“Plants contain a variety of toxic compounds that help to deter herbivores and insects from eating them,” he continued. “A classic example of this is milkweed that contains a milky sap that is an irritant and therefore distasteful. It is also poisonous.”
Plant poisonings not only causes death loss but can also cause economic and reproductive losses.
Producers also incur additional expenses associated with spraying herbicide to control these plants, he said.
Each species of animal has different susceptibility levels to plant poisoning, Knight explained.
“Sheep and goats have more carbonic acid in their saliva, so they can consume more poisonous plants. Horses have an entirely different digestive system than cattle, so they can consume feed with nitrates,” he said.
Some plants, like locoweed, are poisonous because they have developed a mutually beneficial relationship with specific fungi that, when growing in the plant, produce a toxic alkaloid poisonous to horses and livestock, Knight said.
“There are numerous native range plants that are potentially poisonous to livestock, but rarely is an animal poisoned by eating a few mouthfuls of these plants,” he explained. “Livestock poisoning occurs most often when rangeland is overgrazed, and animals are forced to eat whatever is available. Feeding hay that is full of weeds can have similar repercussions. Make sure you know what is put up in hay.”
Plants causing sudden or acute death will do so within a few hours of the onset of clinical signs. Most of the time, animals are found dead before physical symptoms appear.
Native plants causing sudden death are water hemlock, some species of milkweed, death camas, larkspur and choke cherry.
“Poison hemlock is an invasive weed that, if eaten before it matures, can also cause fatalities,” Knight stated.
Water hemlock is a perennial that grows in wet or marshy environments. It can grow four to six feet by maturity. Water hemlock has hollow, compartmentalized stems with leaves that are compound, alternate and pinnate with leaflets five to eight centimeters long and one to two centimeters wide. It has many small, white flowers.
The tuberous roots produce a highly toxic, pungent, yellowish fluid when cut, Knight explained.
A lethal dose of water hemlock roots is less than 0.5 percent body weight.
“The potential for water hemlock poisoning is high in horses and livestock grazing pastures that have marshy areas or where animals have access to stream or river banks where the plants tend to grow,” Knight explained. “Animals find water hemlock palatable, especially the new leaves in the spring.”
Consuming sorghum hay also has the potential to be toxic for some animals.
“Although horses are rarely fatally poisoned by plants containing cyanogenic compounds, horses, cattle and sheep can develop a syndrome of posterior ataxia and urinary incontinence after consuming sorghum hay for a period of weeks,” Knight said.
Poisoning causes degeneration of the white matter of the spinal cord, hind leg ataxia, tail paralysis and urinary bladder paralysis leading to incontinence. The degenerative changes in the nerves are irreversible, and fetal limb deformities have been reported in foals and calves whose dams are fed sorghums during pregnancy.
Knight also encouraged producers to watch out for milkweeds. A few species of milkweed can be poisonous to livestock, horses and domestic fowl, especially when other forages are scarce or milkweeds are incorporated into hay.
Milkweeds contain a variety of toxins that affect the heart, digestive system or the nervous system. The highest concentration of cardenolides is found in milky sap, but all parts of the plant are toxic. Milkweed remains toxic when dried, so animals consuming the dried plants in hay are at risk.
As little as one kilogram of green milkweed plant material is lethal to an adult horse. Clinical signs usually start about 12 hours after consumption and consist of depression and labored, slow respiration. Horses may show colic and diarrhea.
There are 13 species of Death Camas in North America that are poisonous to livestock, horses and alpacas. All parts of the plant are toxic, especially new growth and bulbs.
Death results from respiratory paralysis.
Most poisonings occur in the spring because Death Camas shoots appear before grasses and other plants and are considered particularly palatable to livestock.
Horses should be kept away from locoweed, added Knight.
At least 2,000 species of locoweed exist in western North America. However, few are toxic.
“A few species of locoweed have long been recognized as important poisonous plants affecting horses and livestock, causing more overall economic losses to the livestock industry than any other group of plants,” Knight stated.
Horses are particularly susceptible to locoweed poisoning.
“Animals find locoweed palatable and will graze the green plants readily in the spring before grasses emerge from dormancy,” he said.
Horses exhibit the most distinctive signs of locoism, characterized by changes in normal behavior including marked depression, drowsiness, blindness, abnormal gaits, marked difficulty in walking and backing-up. Abnormal attempts at chewing food and spastic jaw movement may also be observed, Knight said.
Affected horses also show unpredictable behavior, such as rearing on their hind legs and falling over backwards, along with sudden periods of sudden and extreme excitement.
Riding loco-affected horses is dangerous.
If clinical signs are recognized early and the horse is removed from locoweed, clinical improvement will occur, but it may take several months for abnormal behavior to resolve completely, Knight noted.
Horses should not be allowed to graze locoweed in the spring when other forages are unavailable. Since locoweed is palatable and nutritious, animals will readily consume it.
Locoweed can be controlled with herbicides, but dried locoweed stems remain toxic at the end of the growing season, Knight explained.
Overgrazing or overstocking pastures will increase the potential for locoweed poisoning.
Black henbane added to Wyoming’s state list of designated noxious weedsWritten by Natasha Wheeler
With a unanimous vote on Feb. 11, the Board of Agriculture passed a resolution to add black henbane to the state’s list of designated noxious weeds.
“At the public hearing, there were folks who commented in support of the resolution, but there were no comments opposed to it,” comments Slade Franklin, weed and pest coordinator with the Wyoming Department of Agriculture.
The board took action on the resolution in a business meeting immediately following the public hearing.
“It was a straightforward hearing, and there wasn’t anything too concerning,” he notes.
Black henbane has already been listed in numerous Wyoming counties as a noxious weed.
“Concern had grown to almost all 23 counties in the state. It was getting to the point where we needed to start addressing it from a state level,” Franklin says.
The weed is especially prevalent along pipelines and in riparian areas.
“Black henbane likes disturbed lands,” he explains. “Especially in the southern part of the state where vegetation is scarce, more weeds in general are likely to come in after a disturbance such as when a new pipeline is put in.”
In Teton County, the weed is often a problem around new home construction.
“It is diverse in terms of areas that it can attack,” Franklin notes.
When the plant reaches maturity, a thickened lid pops off of the urn-shaped fruit, spilling black seeds. A single plant can produce up to half a million seeds.
“I’ve had reports on black henbane from areas all over the state,” states Franklin.
Last year, the Board of Agriculture wrote a letter to the Weed and Pest Council, asking them to consider adding black henbane to the state’s designated weed list.
“The rules and regulations state that a resolution must start with a weed and pest district request to the council, who then moves it forward to the Board of Ag for consideration,” he says.
After the board’s request, three different weed and pest districts moved forward with a resolution.
“We moved one of the resolutions forward,” Franklin states. “It is the 26th weed on our designated list.”
Black henbane is an annual or biennial plant that grows up to three feet tall, and the entire plant is covered with greasy hairs. Leaves are up to eight inches long and six inches wide, shallowly lobed and heavily scented.
“It is a poisonous plant, so there are also concerns from an agricultural perspective about its toxicity,” adds Franklin.
Generally, livestock will avoid the weed unless it is the only available forage.
“There is potential for concern in targeted grazing or with livestock that is not used to it,” he adds.
In controlled dosages, alkaloids from black henbane are used in medications but the plant is also poisonous to humans.
“Black henbane is treatable,” Franklin continues, noting that there are several herbicide options for control of the plant.
Escort and Tordon are examples of herbicides that work effectively for controlling the weed.
“It’s not a matter of ‘can we treat this,’ it is a matter of ‘do we need to treat this,’ and that is why it has made it on the list,” Franklin explains.
Other common names for black henbane include insane root, stinking nightshade, fetid nightshade and hog’s beam.