By Dwight Lingenfelter
At Ag Progress Days last week, the most frequently asked question at our booth was about how to control horsenettle in pastures and hayfields. With a wet spring and a dry summer, it has thrived and is causing problems in grass forages. Below are some details about this stubborn weed and some suggestions to manage it.
Biology: Why It's So Aggressive
Horsenettle is native to the United States and is an aggressive warm-season creeping perennial. It actively grows from May to early September, and its shoots sprout from roots during mid-spring and continue to emerge through summer. It can also germinate from viable seed. Horsenettle can thrive in hot weather and is drought-resistant because of its deep root system. It can tolerate poor soil conditions (including low fertility) and can grow in many different soil types. Horsenettle prefers sunny environments but can tolerate moderate shade and is commonly found in overgrazed pastures. Its foliage is sensitive to cold temperatures, so its top growth is usually killed by the first frost.
Toxicity Problems in Forage
Horsenettle affects forage quality and stocking density for a few reasons. Due to its sharp prickles, it can cause irritation and injury to soft tissue in the mouth and throat of livestock if consumed. It also has certain toxic qualities, but this can widely vary depending on environmental conditions. Green berries are usually more toxic than mature berries of horsenettle, but the whole plant can be poisonous if ingested by livestock or humans. Toxicity is usually higher in late summer/fall compared to spring.
Source : psu.edu