Annual weeds have always been a problem to the cranberry grower, but certain changes taking place in the bog environment have caused an increase in the population of annual weeds in some areas in recent years. The decline of soil acidity as a result of the long term use of alkaline water for frost flooding, coupled with the well drained bog culture recommended for Wisconsin growers, have produced an environment to which certain annual weeds are adapted. With some species, particularly common ragweed (Ambrosia artemisiifolia), the extensive use of petroleum products as herbicides has encouraged the invasion of annual weeds following the suppression of oil sensitive perennials.