Pesky Summer Weeds

Home Grown  by Keith Reed
The Extension office is starting to get calls on a pesky weed that pops up in high numbers every few years. Prostrate spurge, also known as spotted spurge, is a common summer annual broadleaf weed that ordinarily does not garner much attention.

Prostrate spurge, Euforbia maculate, is easy to identify once you’ve seen it. It is a very low growing plant rarely getting tall enough for a lawnmower to touch. It can sometimes be mis-identified as the common goathead (puncture vine) but correct identification is easily made by breaking a stem, where you will find a milky white sap. Also, spurge does not produce a “sticker” as does the goathead.

Prostrate spurge is normally kept under control with a healthy lawn in conjunction with a quality pre-emergence herbicide program. If this defines your landscape, I would not assume you or your lawn care company has “failed” at controlling weeds, it is just one of those unusual circumstances. However, I realize that does nothing to solve the current problem, so here are some suggestions for dealing with this weed right now.

As this is a broadleaf weed, it responds well to treatment by a number of broadleaf weed control products. As is often the case when dealing with pests, there is a “but wait” associated with the use of these lawn care products. Bright sun and high temperatures can contribute to an unacceptable level of turfgrass (or off-target, possibly meaning your neighbors garden) damage this time of year, especially as the weeds mature and higher rates of herbicide are needed to get reasonable control.

As mentioned, it is very important to note that broadleaf herbicides can easily cause damage to garden vegetable or ornamentals, either by direct contact or by vapor drift. DO NOT use these products on windy days or outside the application guidelines outlined on the label.

Prostrate spurge has also popped up in concrete cracks, patios and landscape beds. In these situations, another control option is a non-selective herbicide. These products typically do not have the vapor drift issues that come with broadleaf herbicides.

This weed is reasonably easy to control mechanically, either by hoeing or pulling up. Unless you have large expanses of the plant, this is perhaps your best option right now. It is not necessary to get all the roots, a snip at the surface should take care of it.

One final note on prostrate spurge: As a member of the Euforbia family, the sap of this plant can cause minor skin irritation for those that are allergic to it. If you notice your hands itching after weeding the garden, this could be your culprit.

For more information of this or any other horticultural topic, you can contact Keith Reed, the Horticulturist in the Payne County Extension office. Keith can be reached via email at keith.reed@okstate.edu, phone at 405-747-8320, or in person at the Payne County Extension office, located at 315 W. 6th in Stillwater.

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