Over the past few weeks, I have been getting some calls on pasture and hayfield weeds over fears of toxicity to livestock. This is a reasonable fear, as some of the common weeds found in Clinton County can certainly cause livestock sickness and or mortality. For this reason, I recommend that a landowner with livestock be scouting each week for weeds that could possibly harm the animals.
Most of the time when I get calls on weeds the first question asked is, “What can I spray to kill this weed?” We can find the answer on chemical control for that specific weed, but I also add that chemical control is only one method of weed control, one to use but not depend solely on. Not only that, but something else to understand is that there is a threshold for chemical weed control, usually weeds that are getting close to the reproduction stage (going to seed) they become a lot harder to kill using chemicals, chemical control should be happening when the weed is four inches tall or less.
Other methods of control could be mowing regularly and preventing the weed from going to seed and slowly depleting root reserves, or managing soil health, because many weeds like soils with out of balance pH and low soil nutrient values. Using all of these tools together creates something called Integrated Pest Management, or IPM. Here are a few of the weeds I am seeing around Clinton County in the past few weeks.
– Horse nettle (Solanum carolinese) this weed is common throughout southern Ohio, and it isn’t really a nettle, it’s in the Nightshade family. The fact that it is a Nightshade makes it toxic to livestock. Plant toxicity varies depending on stage of growth and time of year, unripe berries are more toxic than ripe berries, berries are more toxic than leaves and stems. Highest toxicity is in the late summer and fall. Management of this weed can include the use of systemic herbicide, as well as regular mowing of the weed that will deplete the roots of stored energy. The best time to mow this weed is after flowering but before berry production. Flowers can be white to light purple.
– Buttercup (Ranunculus bulbosus) very common in livestock pastures that have low pH, low soil fertility, and compaction. This weed grows close to the ground, has yellow cup-shaped flowers that are shiny. Cultural control is a good management tool for this weed, as improved soil health and make growing conditions for this weed less than ideal. Herbicides containing 2,4-D can also be used. This weed is known to be mildly toxic to ruminants and more toxic to horses.
– Poison Hemlock (Conium maculatum) These tall weeds that grow along roadsides and in wet areas can also be found in a pasture or hayfield. They have a white flower can be misidentified with plants like queen Anne’s lace, Yarrow, or even flowering elderberries. This is an extremely toxic plant for livestock when ingested. Poison Hemlock is a biennial weed, meaning that within the first growing season after germination, the weed will only reach a rosette stage, the following year will go into reproduction and go to seed. Best chemical control of this weed is within the first year when in the rosette growing stage. Manual removal by mowing before the weed goes to seed is the best way to control this weed through cultural management. This weed is not palatable and has a strong odor, so livestock typically do not eat this weed on purpose. The issue is that if baled into hay and eaten on accident, it does not take much to kill livestock. Unlike some other poisonous weeds that lose toxicity when dried down into hay or ensiled, Poison Hemlock maintains it toxics still.
These weeds are not the only poisonous weeds found in pastures and hayfields throughout the county, but these are some that I have seen and worked with livestock owners to manage. In chemical control remember that the label is the law, and that means that the herbicide in question can only be applied to weeds that it is labeled for, at the correct rates, and following all restrictions. Also make sure to follow the rules for person protective equipment (PPE) to keep yourself safe while applying herbicide. Its important to remember that cultural control methods such as manual removal and soil health as well as chemical control are all options that can work together to manage weed pests on your property.
Brooks Warner is the Ag & Natural Resources Educator at OSU Extension Clinton County.
