Cattail emergence was poor in early 1990 due to drouth conditions, so cattails tended to be small, which may account for the reduced control by Rodeo applied on July 5, 1990. Adjuvants at Lakota. There are several possible explanations for the differences in cattail growth between Dion Marsh and Fisk Lake. Cattail density at Fisk Lake increased dramatically from seedlings in July 1991 after several inches of rainfall were received in late June and early July 1991. Fisk Lake is a mud flat and is very shallow where the experiments were established so it dried out rapidly, whereas Dion Marsh is deeper and water did not retreat as fast.
Cattails have a large rhizome system that enables the plant to regrow after the topgrowth is killed.
Depending on effectiveness of the herbicide treatment and marsh site characteristics, especially water depth, cattail reestablishment may occur within 1 yr or may take 3 to 4 yr. Therefore, treatments should be evaluated for 2 to 3 yr after application before strong conclusions are made about the treatment. The research presented in this report is based on 1 yr of data and herbicides were applied during a drought, so the data should be interpreted with caution. Cattail control was achieved with Rodeo applied at any time during the growing season, but late July tended to be the optimal time for cattail control. Diammonium sulfate added to Rodeo did not improve cattail control and may be antagonistic to Rodeo.