It has been interesting this year. The abundant rain filled our lakes, greened our gardens and put people back to work in agriculture but it also produced A LOT of weeds. The weeds have sprouted in stages. We go out into the garden and take care of the weeds and in 2 weeks different weeds are sprouting.
Right now, spurge is sprouting. At first glance, spurge is hard to see but when you see it, then it is hard to miss.
Spotted spurge is an annual plant native to the eastern United States. In California, it is the most common species of the spurge family, which also includes creeping spurge and petty spurge. These weeds invade many of the state’s crops, affecting vegetables, trees, citrus, turf, ornamental beds, and container ornamentals. Management of all the spurges is similar.
Spotted spurge grows close to the ground, often forming a dense mat. Its dark green leaves, which grow in pairs called “opposites,” are 1/8 to 1/2 inch long and about 1/8 inch wide. Frequently a red spot will mark the leaf halfway down its center vein.
Flowers, fruit, stems, and leaves are hairy. The short stems have a separate stipule—or little scalelike appendage—at their base, although you may need a 10X hand lens to see them. Broken stems and branches secrete a milky, poisonous sap
Spotted spurge produces tiny, pinkish flowers that consist only of stamens and pistils grouped in small, flowerlike cups, called cyathia, in the leaf axils, the area where the leaf joins the stem. The fruit is a three-celled seed capsule that is 1/16 inch or less. Each cell contains one seed that is about 1/25 inch long. The plant’s central taproot system is capable of extending more than 24 inches into the soil.
Although spotted spurge is the major spurge weed in California, six other species of spurges appear regularly as weeds in the state.
The primary method of managing spurges is prevention, since controlling these weeds is very difficult once plants have established themselves. Avoid bringing seeds into uninfested areas by using weed-free planting seed and uncontaminated planting stock. Clean work clothing and machinery such as lawn mowers to remove any seeds that might be present and remove spurge plants as soon as you discover them.
Constantly monitor infested areas, so you can mechanically till, or hand pull new plants before they produce seed. Take care as you weed, since plants that you hand pull often break at the stem, leaving the root and several buds or a single stem from which regrowth is possible. Wear gloves when you hand pull since the sap can be a skin irritant. Mowing is an ineffective method of control since most species grow closely to the ground.
When planting new, container-grown ornamentals and ornamental beds, be sure to use sterilized or weed-free planting mix. When purchasing plants for ornamental beds, avoid those with spotted spurge infestations. Mulches can effectively limit spotted spurge if they prevent light from reaching the seed.
Preemergent herbicides can help prevent spotted spurge outbreaks if you apply them in late winter before weed seeds germinate. Time the application, so it occurs before the soil temperature exceeds 55° to 60°F at a depth of 1 inch.
Postemergent herbicides are available to home gardeners. ■
