Tuesday, August 3, 2010

Where Did All The Weeds Come From?

One of Princeton Landing’s most precious assets—its expansive, pristine turf—is in jeopardy. High-quality lawns like ours are usually admired for their uniformity. But this year our lawns are filled with noxious, invasive weeds. A “weed” is simply a plant that grows where it is not wanted, but the two weeds discussed here—crabgrass and spurge—are considered undesirable in almost any situation. Their different leaf shapes, sizes and colors prevent turf grass from achieving its optimum growth and the uniform appearance that is so highly valued.

Crabgrass (genus Digitaria) is a bright green grassy annual with stems that extend out like the legs of a crab. It grows in the heat of midsummer when more desirable grasses are semi-dormant and offer little competition. An adult plant can reach 18 inches tall and 20 inches wide and produce up to 150,000 seeds. Crabgrass plants are killed by the first hard frost in fall, but their seeds survive through winter. Applying a pre-emergent herbicide in spring is the best way to control crabgrass, but if that opportunity is missed, special herbicides can be an effective treatment.

Our most common forms of spurge (genus Euphorbia; sub-genus Chamaesyce) are Spotted Spurge (Chamaesyce maculata) and the similar Prostrate Spurge (Euphorbia prostrata or Euphorbia supine). Both are summer annuals that form dense mats of stems and leaves on the ground. These mats, which can reach 16 inches in diameter, choke out desirable lawn grasses. Spurge can be eliminated by applying a pre-emergent herbicide in spring. Post-emergent herbicides are much less effective.

The prevalence of these weeds indicates that Princeton Landing’s landscape is in trouble. Neither the weather nor our landscape company are to blame. When the Landscape Committee chose not to use a pre-emergent herbicide last year and to delay its application this year, they gave these weeds a huge advantage in the ongoing battle for control of our lawns. Their actions affect the appearance of our community and the value of our homes. It will now take a lot of time and effort to restore our turf.


Derek Krabill said...

John, you appear to be quite upset with the landscape committee for their choice to not use chemical fertilizer last season. While the immediate state of the lawns or increased poison ivy are issues of concern, I find that the committee's efforts to rely on organic methods of weed control admirable. It is still desirable, in my opinion, to identify non-chemical means of control.

jplatimer said...

Dear Mr. Krabill,
Thank you for your thoughtful comment. It deserves a detailed reply which I will post in the next day or two.
Jon Latimer