Spotted spurge (Euphorbia maculata) is an annual weed in the spurge family. It grows close to the ground and forms a dense mat of vegetation invading gardens, cultivated agricultural areas, cracks in sidewalks, and thin lawns. It grows well in poor, compacted soil and loves full sun. Spotted spurge can grow up to 2 feet in diameter, produces seeds within 5 weeks of germination, and can produce two to three generations in a growing season. Spotted spurge is poisonous to sheep and has been shown to kill animals that consumed as little as 0.62% of their body weight within a few hours.

Spotted spurge has small elliptical-shaped, bright green leaves that have an irregular-purple spot in the center of each blade. The leaves are arranged opposite each other on the pink stems that radiate from a center underground taproot. A thick milky sap will exude from any point of the plant that is broken off. 

Integrated Pest Management (IPM) Options:  

• Cultural – Applying a mulch layer 3 inches thick on planting beds will reduce seed germination. Soil sterilization by covering the soil with sheets of clear plastic for 4 to 6 weeks during the summer can effectively reduce the number of seeds in an area where temperatures are above 90°F.

• Mechanical – Hand-pull any plants before seed is set. Remove as much of the root as possible. Make sure to carefully dispose of plant material to ensure seeds are not left behind. Mowing is an ineffective way to control spotted spurge because of its low growth habit. Hand pulling or tillage is the preferred method of mechanical weed control, just be aware that any plant material can vegetatively reproduce and sprout new plants.

• Chemical – Preemergent chemicals can help prevent outbreaks of spotted spurge if you apply them in late winter before weed seeds germinate. Postemergent herbicides are also available. 2,4-D, Dicamba, Fluroxypryr, Flumioxazin, and MCPP have all proven to provide good control of spotted spurge, for best control use a combination of one or more of the herbicides listed. As with all chemical pest control, always read and follow herbicide label directions!

Tom Jacobsen, University of Idaho Extension Educator in Fremont County. (208) 624-3102 [email protected] and Justin Hatch, University of Idaho Extension Educator in Caribou County. (208) 547-3205