Although weeds plague our lawn and garden every year, it seems that each year a particular weed takes center stage. One year it was wild violets. The next year it was purslane. A few years ago, we had elm seedlings sprouting everywhere. This year the villain in our yard is a plant we call mimosa weed (Phyllanthus urinaria) because its foliage looks similar to the familiar mimosa tree.
This is a nasty fellow. It invades lawns and flower beds indiscriminately and it is sneaky. It germinates later than most weeds, so late that our spring application of pre-emergent herbicide was not effective to prevent it in our lawn. It also develops seeds as a very small plant and they hide on the undersides of the leaves. So while you are thinking you have time to weed before that critical reseeding time, it is already developing seeds. It has a strong stem and large taproot, so it is not so easy to pull up. Roundup is effective on it but I try to avoid using Roundup when I can, both because it can cause damage to nearby plants and because I'm not convinced that it is not a dangerous chemical (even though there is no scientific evidence to support this idea).
Jack and I have put in a lot of hours pulling up mimosa weed this summer, and I'm determined to get ahead of it next year. Our main problem spots this year were a bed that was not well-mulched and areas of the lawn where the grass was thin. We've been working to get the lawn in better shape this summer because dense, healthy turf is the best deterrent for all weeds in the lawn. Also, next year, we may change our pre-emergent for the lawn to one that is more effective in controlling this particular weed.
If your garden has been plagued by this particular weed, you might find this factsheet useful for more suggestions about how to control it, including a complete discussion of the various chemical controls available.
Wonder which weed I'll be complaining about next year . . . .