By Eric Jones and Philip Rozeboom
Waterhemp is one of the most-difficult weeds to manage in South Dakota row crops. While herbicide resistance is a great factor in the difficulty of managing this weed, the biology of the species plays an important role as well. Waterhemp can grow 1 inch a day if conditions are favorable (i.e., warm temperatures and adequate soil moisture) which can lead to increased competition with crops to potentially reduce yield and harvest efficiency.
Waterhemp Biology
Waterhemp is a dioecious species, meaning there are separate female and male plants. The male plants flower first to ensure there is viable pollen for the flowers of the female plants to produce seed. If waterhemp plants are not effectively managed, a single female plant can produce anywhere from a few hundred to several hundred thousand seeds.
Source : sdstate.edu