Oldfield Cinquefoil (Potentilla simplex) Control in Cranberry (Vaccinium macrocarpon)

Abstract

Greenhouse and field herbicide evaluation, flooding, and soil saturation studies were conducted to investigate the control of oldfield cinquefoil in cranberry. Chlorimuron ethyl and dichlobenil were found to be promising herbicides for control of this weed in both greenhouse and field studies. The number of leaves, leaf area, shoot, root, and total dry weight of oldfield cinquefoil were reduced by dichlobenil at 1.1 to 4.5 kg ha-1and chlorimuron ethyl at 17.5 to 35 g ha-1, at 12 wk after treatment. The higher rate of dichlobenil, however, caused reduction in cranberry height and total dry weight. Field treatment at time of cinquefoil emergence did not provide adequate weed control. Postemergence application to cinquefoil of 4.5 kg ha-1dichlobenil, 35 g ha-1chlorimuron ethyl, and 2.2 to 4.5 kg-1ha terbacil reduced the number of leaves and shoot dry weight. Only terbacil at 4.5 kg ha-1reduced cranberry shoot and fruit fresh and dry weight. Flooding for up to 72 h did not affect oldfield cinquefoil growth. At 22/18 C, 4 wk of soil saturation reduced runner development and fresh and dry weight of oldfield cinquefoil. At 13/9 C, no runners developed in either saturated or control soils, and there was no effect of soil saturation on fresh and dry weights. This suggests that oldfield cinquefoil grows better in an unsaturated soil condition, but needs a relatively warm climate to develop.