In my front yard is an area of Dymondia ground cover. Dymondia is a low-growing plant that looks a lot like grass, each leaf having a white stripe down the middle. The bed is liable to weeds, especially including spotted spurge, Euphorbia maculata. The spurge is an annual, whose seeds will not germinate unless they have light, so a dense, healthy mat of desirable plants will suppress it. However, any bare spot is liable to host a spurge plant, which spreads out quickly, smothering surrounding plants and can bear thousands of seeds (which can stay dormant for years) in as little as five weeks. “The primary method of managing spotted spurge should be prevention—it is very difficult to control this weed once it is established. Avoid bringing spotted spurge seeds into uninfested areas: use weed-free planting seed and uncontaminated planting stock” say the folks at Davis. And just out of sheer cussedness, like all euphorbias, the stuff is poisonous.
One would think one could just spray the bed with something, but Dymondia is a dicot despite its grasslike appearance, so the sort of selective weedkiller one sprays on lawns (Agent orange–2-4D–and related chemicals, actually), that don’t affect monocots, will kill it as well .
This means only six approaches are practical:
(1) Spray Roundup on every spurge, creating circles of collateral damage/dead Dymondia in which new spurges will sprout. This is a really stupid plan, but I have Roundup and a sprayer and I’m in a hurry to do something.
(2) Actually, the spurge is in its last throes. Observing more and more of it every week has nothing to do with the imminent development of a beautiful carpet of Dymondia, and acting or even speaking as though the spurge is advancing will undermine the whole project.
(3) If it walks like a duck and talks like a duck…Dymondia looks like grass, and this monocot/dicot stuff is nowhere in the Bible and anyway much too complicated, something a bunch of pointyhead scientists at UC Davis would say. Anyway, a sprayer and 2-4D is what I have, so I’m going for it: can’t let the weeds sense weakness or indecision.
(4) Wait until the bed does whatever it wants, and declare that’s what I intended all along.
(5) Roundup the whole bed, killing everything; apply a half-inch of sterile soil on top; and replant it, perhaps with gravel or concrete instead of plants. Call it the Victory Patio.
(6) Go after the spurge plants as they emerge and before they set seeds, pulling them carefully to minimize damage to the surrounding Dymondia. Doing this, it’s easy to break them off leaving the root which then resprouts. Retail, one-by-one, tedious, frequent, repetitive, focused weeding [even with Dano’s very much appreciated technological tip in the comment].