Black nightshade in corn residue

Have you noticed any black nightshade in your corn stalks that you are grazing or plan to graze? If these fields have too much black nightshade, be careful, it might be toxic.

Black nightshade is common in many cornfields in the fall, especially those that had hail damage in the summer or any situation where the corn canopy became thin or open. It usually isn’t a problem, but if the density of nightshade is very high, there is the potential that it could poison livestock that graze many of the plants. Almost all livestock, including cattle, sheep, swine, horses, and poultry are susceptible.

Black nightshade plants average about two feet in height and have simple alternating leaves. In the fall, berries are green and become black as the plant matures. All plant parts contain some of the toxin and the concentration increases as plants mature, except in the berries. Drying as hay or after a freeze will not reduce the toxicity.

It is very difficult to determine exactly how much black nightshade is risky. Guidelines say that a cow would need to consume three to four pounds of fresh black nightshade to be at risk of being poisoned. These guidelines, though, are considered conservative since there is little data on the actual toxicity of nightshade plants. Also encouraging is that reports of nightshade poisoning have been very scarce in the past.

Fortunately, even though nightshade plants remain green fairly late into the fall, cattle usually don’t appear to seek out nightshade plants to graze. However, green plants of nightshade might become tempting toward the end of a field’s grazing period, when there is less grain, husks, or leaves to select.

So common sense and good observation must be your guide. Scouting fields to estimate the general density of nightshade plants will help you determine any potential risk. Secondly, and particularly near the end of a field’s grazing period, closely observe what the cattle are eating to see if animals might be selecting nightshade plants.