What is horsenettle?

Horsenettle is a spiny, native perennial in the nightshade family, related to tomatoes and potatoes. Horsenettle identification is easy once you know what to look for, but getting rid of it is another story. It comes back every year from a deep, creeping root system that breaks into pieces when you dig.

It’s a familiar headache in pastures and hay fields, where animals avoid it and it slowly takes over. In yards it shows up in gardens, along fences and in thin lawns, especially on sandy or well-drained ground.

All parts are poisonous, and the spines make hand pulling unpleasant, so it’s worth taking seriously.

Horsenettle identification: what to look for

Horsenettle has several features that make it stand out:

• Spines: sharp, straw-colored spines on the stems, leaf stalks and along the midrib and main veins on both sides of the leaf.
• Leaves: alternate, oblong to egg-shaped and 2 to 6 inches long, with wavy edges or a few shallow lobes. They feel rough from tiny star-shaped hairs, and flea beetles often riddle them with small holes.
• Flowers: white to pale violet five-pointed stars about an inch across, with a bright yellow cone of anthers in the middle, like a tomato or potato flower. They bloom from early summer into fall.
• Berries: smooth and marble-sized, green with darker stripes at first, ripening yellow and wrinkling as they dry. They often hang on through winter.
• Roots: thick, deep creeping roots that sprout new shoots, so plants show up in patches.

Where it grows in Pennsylvania

Horsenettle grows across the state. It’s most common in pastures, hay fields, field edges, gardens, roadsides and lawn edges with sandy, gravelly or well-drained soil, but it isn’t picky.

In horse and cattle pastures it often expands because animals graze around it, leaving it free to spread. In gardens, tilling chops up the roots and spreads them, so a few plants can turn into a big patch. Seeds spread when birds and other animals eat the berries.

Horsenettle look-alikes

A few plants look similar at first glance:

• Eastern black nightshade has similar flowers and leaves, but it’s an annual with no spines, smaller drooping white flowers and berries that ripen shiny black.
• Bittersweet nightshade is a climbing vine without spines, with purple swept-back petals and bright red berries.
• Ground cherries look similar in form but have no spines, and their fruit is wrapped in a papery husk.
• Thistles are spiny too, but they have deeply lobed, prickly-edged leaves and purple brush-like flower heads.

If it has spines on the leaf veins and star-shaped flowers with a yellow cone, it’s horsenettle.

How to get rid of horsenettle

Plan on a multi-year effort. The goal is to wear down the root system.

Hand and mechanical. Pulling one plant won’t do much; the roots break and resprout. Still, in a garden or bed, digging and repeatedly cutting new shoots at ground level, wearing heavy gloves, will eventually starve the roots. Don’t till an infested spot, since that spreads root pieces. In pastures and rough areas, mowing several times a summer stops berry production and weakens the plants over a few seasons.

Cultural. Horsenettle takes advantage of thin cover. In lawns, mow at 3 to 4 inches and keep turf thick with fall fertilizing and overseeding. In pastures, avoid overgrazing, rotate paddocks, fertilize and lime according to a soil test, and reseed thin areas. In beds, heavy mulch slows it but won’t stop it on its own.

Chemical. Extension recommendations for horsenettle rely on systemic broadleaf herbicides that move into the roots. In lawns, products containing 2,4-D, dicamba or triclopyr, often in combination, work best with repeat treatments. In pastures and hay fields, extension sources list aminopyralid-containing products, some combined with 2,4-D. Research points to the flowering stage, before berries form, as the best timing, with follow-up on regrowth in late summer. Glyphosate can be spot-applied in beds but kills anything green it touches.

Read and follow the product label, because the label is the law, and check that it’s labeled for your site, whether lawn, pasture or bed, and any grazing restrictions. Applying herbicide for hire in Pennsylvania requires a PA Department of Agriculture pesticide applicator certification, so pasture-scale jobs belong with a licensed vegetation-management company.

Keeping it from coming back

Horsenettle is persistent, so stay on it. Check treated areas every summer and spot-treat or cut new shoots before they flower and set berries. Pick up berries where you can, since every one is full of seeds.

Keep turf and pasture grass thick, and don’t move soil from infested areas to new beds. In a vegetable garden, keep it in a separate area and handle it by hand, without spraying near food crops.

Questions we get about horsenettle

Similar weeds

Eastern Black NightshadeSolanum ptycanthumBittersweet NightshadeSolanum dulcamaraCanada ThistleCirsium arvense