Horsenettle is part of the nightshade family, which includes tomatoes and potatoes. However, it is not considered an edible plant like its potato and tomato counterparts. The scientific name is Solanum carolinense, and it is regarded as one of the most challenging plants to eradicate because it resists most efforts at control. It is known in some places as Carolina nettle or bullnettle and is a perennial weed that produces by both seed and rhizome.
This invasive weed is easily identified. They emerge in late spring as shiny leaves with a dark green topside and a pale green underside. Leaf margins are covered with hairs, and leaf midribs and petioles have sharp prickles. Plants have a large and fibrous taproot, which can grow to depths of up to 10 feet deep in soil. Flowers are very easy to distinguish. They have clusters of five-petaled flower heads that form a conspicious star with yellow anthers in the center. The plant produces berries, which start off as pale green in color and turn yellow as the plant matures. Horsenettle can grow as large as three feet tall, and flowers and berries generally appear in late summer and early fall.
This invasive and difficult weed is native to the southeastern United States and can be found throughout the region. It is also prevalent in the central United States and along the eastern coast. It grows very easily in loamy and sandy soils, though it is found just about anywhere temperate enough to propagate and reproduce.
Part of what makes horsenettle so undesirable is the difficulty in eradicating it. Proper lawn care and weed control measures can help keep this stubborn weed from spreading too badly. It is considered toxic in high quantities to livestock, though illness or death from horsenettle is relatively rare. It is considered unpalatable to most grazing animals, and livestock will usually graze around it in pastures or try to pick it out of hay or feed. Some parts of the plant are more toxic than others with the unripe berries being the most harmful. Because it spreads by both seeds and rhizomes, it can be difficult to manage once established. Deep taproots make the mechanical removal of mature plants difficult as well.
The plant’s root system becomes slightly weakened after mowing. Mowing it down after it flowers stresses the roots a bit more than pre-flowering or fruit-bearing stages. Mowing plants for the first time should be done only after flowering. After that, regular mowing will help keep horsenettle from spreading too badly. It may take several years of regular mowing and stressing the root systems to eliminate this hearty weed. Using an appropriate herbicide after mowing can further help to damage root systems. Because of the depth of the root and the sprawling rhizomes, herbicides have minimal effect on killing horsenettle. Prevention is the best defense against horsenettle. One of its primary ways of introduction to pastures and grazing fields is through feeding hay that carries dried plant material from horsenettle, where it is then excreted in pastures and fields and germinates. Using clean hay with a known source is one of the best ways to prevent the spread and keep livestock safe from the potentially toxic plant.