Spotting Spotted Spurge

Spotted Spurge in Lawn

You may or may not know what spotted spurge is, but chances are you have seen it in lawns and especially flowerbeds during the summer months.   Spotted spurge (Euphorbia maculata) is a summer annual broadleaf weed that is native to the eastern United States and is extremely common here in central California.

It grows very close to the ground and forms a dense mat of pinkish-red stems, deep green leaves with a purple spot in the center, and a center taproot pegging it to the ground.  The taproot may extend down as far as 24 inches! If the plant is pulled or broken, a white, milky latex-like sap will ooze out.  This sap can be irritating to some people’s skin.  Its leaves are in opposite pairs along the stems, and the flowers, stems, fruit, and leaves are covered with tiny hairs.

Spurge usually starts germinating in late March or April as the soil temperatures reach 60 degrees F, but really thrives when soils temperatures are 75-85 degrees F.  With little water and sunlight the seed will germinate successfully.  UC Extension literature states that it can produce viable seed within 5 weeks of germination, but I swear that it seems more like overnight.  A single plant can produce thousands of seeds that can germinate immediately if the conditions are right.  If you have ever pulled up spurge plants you can see the massive amounts of seed left behind on the soil surface.  Ants like to help move these around, too.  Maybe they like the shade it produces or perhaps it is a source of food for them.

Now we know when and what to look for in our search for spotted spurge, but how do we reduce its presence in our landscapes?  Culturally, we can watch for weeds in plants and soils we purchase to add to our landscape.  Try to pull, hoe, or spray plants before they have a chance to go to seed. Mulching the soil surface with 3-4 inches of bark chips can also reduce weed germination by shading the soil below and reducing the needed sunlight for germination.  Anything less than 3 inches is only cosmetic in terms of weed control.  In lawns, thin areas should be filled in with sod or reseeded and then fertilized and mowed at 2 inches or higher to increase the competitive edge over the spurge.

Pre emergent products like Amaze, Preen, or Dimension applied starting in March, will significantly reduce spurge populations through root inhibition.  Multiple applications may be needed for season-long control.  Post emergent products come in both selective (broadleaf herbicides for lawns) and non-selective types such as Roundup where sprays must be carefully directed to hit the weeds only.

Spurge will be here for years and years to come.  If you would like to know more about spurge, or other weeds that you wrestle with, you can call Weed Man at 559-266-1624 or visit our website at Fresno.WeedManUSA.com.