Two experiments in a bay of LaDue Reservoir (Geauga Co., northeastern Ohio) during summer, 1985 demonstrated that removal of Eurasian watermilfoil (Myriophyllum spicatum L.) root crowns with an aquatic weed harvester retarded plant regrowth to quantities well below nuisance levels for 28 days. Nearly summer-long control was achieved following a touch-up harvest on day 42. In contrast, the harvester was used in this bay in 1982 to mow milfoil, leaving intact stumps. The mowed plants regrew to preharvest and control area biomass levels within 23 days. The difference in plant regrowth between these two methods strongly suggests that user dissatisfaction with harvesting could be reduced by using the root crown removal technique. Root crown removal was associated with elevated levels of total phosphorus, chlorophyll, blue-green algae, and seston. The implications of milfoil control with root crown removal, and the associated water quality change, are discussed in relation to recreational and water supply uses of lakes and reservoirs
