After years of drought, poisonous plants and weeds could be emerging
This spring the beauty of green pastures throughout the Ozarks is a special view for producers to behold. The growing grass is a welcome reprieve from past droughts. Though grass is up and thriving, mingled in the pastures may be poisonous plants and invasive weeds that can be harmful, even deadly, to cattle.
“One of the things that impacts the number of poisonous plants that we have is the overall health of our pastures. Our pastures, even our tall fescue pastures, have had a tough time the past couple of years with the drought,” Tim Evans, DVM, Ph.D., veterinary toxicologist with the University of Missouri, said.
Poison hemlock: One of the most common poisonous weeds popping up in fields is poison hemlock. Poison hemlock can be found growing in pastures and hayfields. The weed is highly toxic to animals and humans.
In its early stages, poison hemlock grows basal rosettes. The plant has purple spots on its stem and parsley shaped leaves. As it matures, poison hemlock develops umbrel (small umbrella like flowers) and can grow as high as 6 feet. Its appearance is similar to Queen Anne’s Lace/wild carrot.
The window in which cattle are most likely to eat poison hemlock is when it first starts to grow. As it gets taller and blooms, it is less probable cattle will consume the toxic weed.
However, cattle are more prone to consume poison hemlock or other toxic plants if there is limited forage. If the pastures are not healthy, then cattle may choose to eat toxic invasive weeds because they have few forage options.
Additionally, cattle may inadvertently eat poison hemlock or other toxic plants baled into hay. “One of the concerns we have is when people are making hay that they don’t incorporate some of these plants into that hay because they are still potentially toxic,” Evans said. “If they are in the hay, then you have taken away, to a certain degree, the animal’s choice to eat it or not eat it. Many of them are bitter so animals don’t eat them, but if they are in the hay animals might go ahead and consume them.”
Water hemlock: A toxic weed similar in appearance and toxicity to poison hemlock is water hemlock. It typically grows near water sources but there are exceptions. Water hemlock possesses umbrella shaped flowers similar to poison hemlock. However, water hemlock’s leaf edges are serrated, and it does not have purple spots on its stem.
Additional Species: Producers will want to keep an eye out for additional poisonous weeds such as hemp dogbane, milkweed, nightshades, mustard plants and perilla mint. The leaves on wild cherry trees can also be dangerous. If cattle ingest the leaves on wild cherry trees they can suffer from cyanide poisoning. Even if there are no cherry trees in the pasture, when storms and high winds strike the leaves can be blown into areas where cattle are grazing.
Johnsongrass and sorghum species can pose a danger to cattle as well. The type of toxicity can vary depending on weather patterns (drought and frost), stage of growth, and condition of the plant (damaged or broken).
A common ornamental shrub, the yew, can be cardiotoxic to cattle. Though yews are typically planted in landscaping areas near houses, cattle could gain access to the poisonous plants through a fallen fence, open gate, or if dumped in pastures.
Keeping Cattle Safe: Extension specialists encourage producers to regularly check their properties for potentially harmful and toxic plants. Local extension specialists are available to help producers identify problematic plant species and to offer suggestions of best methods to effectively control them.
Providing an environment where cattle can thrive will help to deter cattle from eating toxic plants. “Animals are much less likely to get into some of the more toxic plants if they have plenty of palatable water, and if they have plenty of grass, hay or other forage to consume,” Evans said.
One of the best ways to keep cattle safe from ingesting poisonous plants is prevention. Specialists suggest producers incorporate land management strategies that work best for their operations in order to reduce invasive weeds and poisonous plants from taking root. Producers may also want to consider using chemical herbicides to control invasive weeds.
