Leafy spurge

About

A deep-rooted Eurasian perennial that takes over prairies and pastures, especially on the Northern Plains and in the Mountain West. Its milky sap irritates skin and can badly hurt the eyes, and cattle and horses avoid or are poisoned by it.

Also called wolf's milk

How to identify it

Look for

Smooth, upright stems 1 to 3 feet tall carry narrow, bluish-green leaves 1 to 4 inches long. In late spring, yellow-green, heart-shaped bracts form umbrella-like clusters at the tops. Every part bleeds a white milky sap when broken.

Look-alikes

Eggleaf spurge has oblong, toothed leaves and white stem hairs. Any plant that bleeds milky sap should be handled with gloves and eye protection.

Where it grows

Pastures, prairies, roadsides, ditches and other untilled ground, especially in dry soil.

When

Shoots emerge from mid-April to early May, it flowers from late May into summer, and seeds shoot out through summer.

How it spreads

Seed pods burst and fling seeds up to 15 or 20 feet, seeds live about 7 to 10 years, and its roots reach 15 feet deep and sprout new shoots.

Most common in

Where it is regulated

Minnesota lists leafy spurge as a Prohibited Control noxious weed and Washington as a Class B noxious weed.

What to do, gentlest first

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

1. Protect eyes and stop the spread Prevent

   Wear eye protection and gloves near it. Clean mowers and vehicles after use, and don't move hay or soil from infested places.

2. Mow before it flowers Prevent

   Repeated mowing before flowering cuts seed production. Pulling and digging usually fail because the roots run so deep and broken roots resprout.

   Mowing won't kill it alone. Bag any plant parts for the trash.

3. Flea beetles and sheep or goats Natural enemies

   Released flea beetles steadily shrink large, stable patches. Sheep and goats graze it well and will eat it repeatedly.

   Hold grazing animals before moving them, since seeds ride in coats and droppings.

4. Picloram, 2,4-D or glyphosate, repeated Conventional spray

   Treat in spring and again in fall, when plants move sugars to the roots; picloram works best, and 2,4-D or glyphosate give partial control. It takes years.

   Read and follow the label. Many lawn and brush herbicides also kill garden plants, so keep spray and drift off anything you want to keep.

Uses, wildlife and pets

Pets

Not listed by the ASPCA; the Minnesota Department of Agriculture notes it is toxic to cattle and horses.