Horsenettle

About

A prickly native perennial nightshade that spreads by deep, creeping roots and is very hard to get rid of once it settles in. Its leaves and yellow, tomato-like berries are poisonous to people, pets and livestock, and its spines hurt.

Also called Carolina horsenettle, horse nettle, bull nettle, devil's tomato, apple of Sodom

How to identify it

Look for

Upright, zigzag stems 1-3 feet tall carry sharp yellowish or white spines, and the leaf veins are prickly too. Leaves are alternate, 2-6 inches, with wavy or shallowly lobed edges and star-shaped hairs. White to light violet star-shaped flowers with yellow centers are followed by smooth green berries that turn yellow and wrinkle, like tiny tomatoes.

Look-alikes

Buffalobur is also spiny but has yellow flowers, deeply lobed leaves and berries wrapped in a spiny husk; clammy groundcherry has densely hairy stems and berries inside a papery husk. Tropical soda apple (Solanum viarum) is often confused with it.

Where it grows

Pastures, hay fields, gardens, crop fields, lawns and roadsides; it does best in sandy or coarse soil but tolerates most soils and some shade.

When

Seedlings appear from mid-May, and new shoots rise from the roots from mid-spring through summer; it blooms about 5-8 weeks after emerging, into fall, and berries ripen in fall and winter.

How it spreads

By seed (up to about 5,000 per shoot) and by deep creeping roots; root pieces as short as about 1/2 inch can grow new plants.

Most common in

Where it is regulated

It is a noxious weed seed under state seed laws in many states, including Colorado, Hawaii and Idaho (prohibited) and Alabama, Arkansas, Delaware, Florida, Georgia, Illinois, Indiana and Kansas (restricted).

What to do, gentlest first

Protect yourself first. Weed killers are a last step; always read and follow the label.

1. Don't chop up the roots Prevent

   Tilling a patch once just spreads root pieces that sprout new plants. If you do cultivate, keep at it repeatedly through summer.

2. Cut or dig shoots again and again By hand

   Remove shoots over and over, especially 1-2 months after they emerge, when the roots' food reserves are lowest. A single mowing only sets it back for about a month.

   Wear thick gloves; the spines are sharp.

3. Spot-treat persistent patches Conventional spray

   In landscape beds, glyphosate as a spot treatment; in lawns, 2,4-D products. Expect to repeat, as it resists some herbicides.

   Read and follow the label. Many lawn weed killers also kill vegetables and flowers, and glyphosate harms any plant it touches.

Uses, wildlife and pets

For wildlife

Bumblebees pollinate the flowers, and quail and wild turkeys eat the ripe berries.

Pets

Nightshades (Solanum species) are listed by the ASPCA as toxic to dogs, cats and horses; signs include drooling, severe stomach upset, diarrhea, drowsiness, weakness, dilated pupils and a slow heart rate. Cattle, horses, sheep, goats and pigs can be poisoned too, mostly in late summer when berries are green.