Dry weather promotes toxic pasture weeds

Farmers and individuals that have grazing animals on pasture have to take extra caution during extended dry periods. Common forage species often go dormant during hot and dry weather causing animals to consume less desirable plants. Some of these plants are toxic to cattle, sheep, goats, or horses. The Ohio State University Extension Beef Team has many resources on weeds that may be toxic to livestock, https://u.osu.edu/sheep/2023/05/30/get-familiar-with-toxic-pasture-weeds. Some of these weeds that may be found this time of year are discussed below, such as buttercup, plants in the nightshade family, dogbane and milkweed, jimson weed, black locust and yew. Many of us may know buttercup for its bright yellow flowers. Two species, tall and creeping, are aggressive perennials that can overtake a pasture during dry conditions. Buttercup contains a bitter, irritating oil called protoanemonin that is poisonous to livestock. The toxicity is reported to vary depending on plant age, growing conditions and freshness of the forage. The oil in fresh plant stems cause irritation and blistering of the animal's skin, lining of the mouth and digestive tract. Generally, animals avoid this plant because of its irritations. However, during dry conditions this may be one of the few green plants available and livestock are more likely to eat it. The toxic oil evaporates quickly, so it is only a problem in fresh forage and not hay. Horsenettle, groundcherry, jimsonweed, and black and bittersweet nightshade all belong to the nightshade family and are toxic to livestock. Plants in this family can often be found in many pastures, but livestock generally leave them alone. There populations will grow and expand in pastures over time. During a drought, livestock may consume the leaf and berries of these plants, which can be deadly to the animal. Unlike the other nightshade members, jimsonweed looks more like a small shrub. You often see this plant around brush piles, hay feeding areas and barn lots. The fruit is encased in a very sharp and spiny outer covering. The leaf is large, waxy and looks something like an oak leaf. This plant is very common and not often eaten. The tropane alkaloids in this plant and seeds are considered extremely toxic when fresh, dried or in silage Dogbane and milkweed are closely related perennial plants commonly found in pastures and hay fields. If you have ever removed a leaf from these plants you will notice a very sticky white and milky substance. The leaves and stems of these plants are considered toxic when fresh or dried. These plants don't mind a little dry weather and consequently become more attractive to livestock during dry conditions. Dogbane and milkweeds are one of the more nasty weeds for livestock and crop fields. The black locust is a common and fast growing tree. Branches have sharp short spines, and the leaves are compound with small, oval leaflets giving it a tropical or fern- like canopy. It often grows along fence rows. In most years, the trees are no problem and stay on their side of the fence. However, during dry conditions, roots sprouts may appear in the adjacent pasture since there is no competition from the forage species. Young and inquisitive animals may find this plant palatable. The bark and new growth are the most toxic. Yew, the last plant to discuss generally does not grow in pastures. Yew and other members of the Taxis family are highly toxic. Unfortunately, individuals may trim or clip yew shrubs and discard the waste over the fence into the pasture. The vegetation and red berries are readily consumed by livestock and are highly toxic. The material continues to be toxic even after it is dried. As pastures are affected by dry conditions, livestock owners need to be aware of their forage availability and identify plants which may be toxic in the grazing area. Livestock should be watched closely looking for signs of distress. A veterinarian should be contacted if plant poisoning is suspected in any animals. If unable to identify a weed, bring it to the Hancock County Extension Office. The Agriculture Extension Agent is trained in weed identification and will gladly assist you.