People have asked me about the purple weed that has emerged in fields and lawns. Most likely that flower is henbit that is an annual forb in Nebraska and a member of the mint family, which means it has a square stem. It has distinctive leaves with crenate and lobed leaf margins and purple to pink flowers. For control, this weed is a winter annual, which means the seed germinates in the fall and the small plants overwinter before growing aggressively in early spring. It flowers in April and May and dies in the hot, dry summer weather. Flowers can produce a lot of seed, which is one reason henbit infestations can increase each year.
Control of henbit this time of year is not recommended because the plant will die shortly. The best option for control is to hand pull the weed in lawns. This has the advantage of minimizing the amount of seed production for next fall. If henbit infestation becomes unacceptable, then apply a PRE herbicide in late summer to early fall. Finally, henbit that does germinate in the fall will be killed with the same POST herbicides that are used to control other pesky weeds like dandelions and creeping Charlie. Other management options for henbit control include, 1) maintaining a healthy and vigorously growing lawn or 2) adding a deep layer of mulch to landscape beds.