Henbit, common chickweed, corn speedwell and other weeds are starting to flower in thinly turfed areas in the north central US. These are all winter annuals and thus germinated last fall, will form flowers and set seed shortly after green-up this spring, and die with the first heat of summer. In established lawns, we would not recommend applications specifically targeted for winter annuals since they will die shortly. If a lawn will be receiving a broadleaf herbicide application in the next few weeks targeting dandelions, that application should hasten the demise of the winter annuals. However, on late-fall or dormant seeded areas where the winter annuals are dominating the struggling seedlings, I would recommend an application immediately to give the desired turf a better chance to compete. The product of choice for new seedlings is Quicksilver from FMC. It is effective in cool temperatures, provides an immediate burn-down and is very safe on seedling turf. Other typical broadleaf products can be damaging to newly-seeded turf. Speedzone from PBI Gordon also contains the same active ingredient as Quicksilver (carfentrazone), but the other three products in Speedzone can damage seedlings.
Zac Reicher, Professor of Turfgrass Science, zreicher2@unl.edu