What is Death Camas and why is it killing Montana cows?
Source: Great Falls Tribune
David Murray, [email protected]
The slender green plant is known as Death Camas, and given the right environmental conditions it can easily live up to its ominous name.
Over the past week, at least four cows in Yellowstone County have died after consuming lethal quantities of the plant. In one case a dead cow was found with a Death Camus plant still hanging out of its mouth.
“I have a producer that had three cows die in one night,” wrote Ag Extension Agent Steve Lackman in an email to Montana State University range scientist Jeff Mosely. “My producer tells me that the camas is the same height as the grass and they are eating it with the grass. My producer is alarmed and thought I may need to put out a warning to (other) producers.”
Significant concentrations of the toxic plant also have been reported in pastures in Custer County, though no livestock deaths have been attributed to it there. Range scientists are cautioning Montana livestock producers to keep on the lookout for Death Camas, warning that current environmental conditions are nearly perfect for a dangerous outbreak.
“It is something that comes around every year,” Chouteau County Ag Extension Agent Tyler Lane said. “It’s probably more common in years following drought because a lot of times after drought there isn’t very much carry-over grass from the previous year. The carry-over grass kind of helps buffer the toxins, so that even though (livestock) might eat the same amount it doesn’t reach a toxic concentration.”
“I think a warning to your producers is a good idea,” Mosely responded to Lackman’s email. “Death Camas is highly toxic in the spring, especially the underground bulb. When soils are moist, livestock can pull the bulb out of the ground and ingest it. Death Camas greens up earlier than most other plants, making it more palatable than other plants in the spring, thereby contributing to livestock eating toxic amounts.”
Death Camas has been a natural part of Montana’s prairie ecosystem far longer than cattle or sheep have grazed here. According to the U.S. Department of Agriculture, Death Camas is a member of the lily family and can be found growing in pastures and fields from Texas to Alaska. Native American tribes were familiar with it, and were careful to avoid Death Camas while picking Common Camas, a native plant food source prized by tribes throughout the Pacific Northwest.
All parts of the Death Camas plant contain a steroidal toxin called Zygacine. Eaten in small amounts, Zygacine causes stomach upset, vomiting and diarrhea. Swallow too much of it and the toxin in Death Camas will trigger varying degrees of paralysis and only rarely death. There is no cure for Zygacine poisoning.
Yet the risk associated with Death Camas is typically low. Given an adequate alternative food source, livestock will usually avoid the green Death Camas shoots. A unique set of environmental conditions have combined to make this year’s emergence of Death Camas a more immediate concern.
“The weather can play a role in the concentration of the toxins,” Mosely said. “The molecular structure of the toxins in many plants change depending on the barometric pressure. When the pressure goes low the molecular structure of the toxin changes into a more toxic form. A lot of time, right as storms are coming in, the plant develops into a more toxic state. Those are times when poisoning is more apt to happen.”
Less than two weeks ago a high-pressure system stalled over Montana, keeping temperatures unseasonably warm. That was followed by a fast-moving low-pressure system that brought a spring snowstorm to many parts of the state. Since then, the weather has remained cool and wet, a near perfect combination to promote the most toxic phase of Death Camas development.
“That fits,” Mosely said of recent weather patterns. “Death Camas is not the only plant that does that. Low Larkspur is also a plant that’s on these spring ranges and can be a problem sometimes.”
Mosely stressed that there is likely a narrow window through which Death Camas will remain a concern. As the grasses continue to mature they will quickly displace Death Camas as a significant grazing source. He recommends livestock producers make a general survey of their pastures, and if at all possible, delay turning animals out into pastures where a significant presence of Death Camas appears to exist.
“By delaying the turnout two things will happen,” Mosely said. “The Death Camas will get more mature and less palatable, and the grass will grow more so there will be more grass in the diet of the animals to buffer the toxin.”
Ranchers and sheep producers who’ve recently added new animals to their herds and flocks should take extra precautions.
“There is some evidence to suggest that the resistance to Death Camas poisoning is genetic,” Mosely added. “For producers who have purchased cattle outside of their immediate area and brought those cows in, those would be ones to watch and to be more concerned about.”
Over the long term, good land management remains the key to reducing the threat from noxious and toxic plants like Death Camas.
“It does become more abundant in pastures that are less healthy, and that don’t have as much grass,” Mosely said. “It’s a native species, but you can exacerbate the problem if you don’t take good care of the range.”
