Knowing the sequence of weed emergence is useful weed management information. It can help producers and ag professionals estimate when certain weeds may appear, particularly after the early emerging species arrive. Such weed emergence sequences have been reported for primarily annual species by several Midwestern states. Many of you have seen the Iowa State (2000) flyer that presents the emergence sequence of 16 common annual weeds for the upper Midwest. An earlier extension bulletin from Iowa State (Buhler et al. 1997) reported on the emergence patterns of 35 annual and 13 perennial weed species.

What has not been done routinely is to monitor the time when perennial and biennial species begin to regrow in the spring. Nor has information on the flowering sequence of a wide array of species at one location been observed and reported. Flowering information for perennial species is important to be able to synchronize tillage, cultivation and systemic herbicide application with the onset of flowering for maximum effectiveness. It is important information for both biennials and perennials in pastures, roadsides, CRP fields and other non-disturbed sites that will be mowed so that this operation is done before weeds produce viable seeds (usually 10 to 15 days after pollination). This paper provides information on the emergence and flowering times and sequences of 82 weed species in a range of life cycles for a threeyear period in southern Wisconsin.