Abstract

Bittercress (Cardamine hirsuta) is a problem weed year round in Southeastern U.S. container nurseries. It readily establishes itself on gravel production surfaces and in containers, producing seeds in 4 to 5 weeks. Gravel has limited adsorption sites for herbicides, and higher use rates are required for control. Many preemergent herbicides provide short-term (3 month) control of bittercress. Sprayable formulations provided more persistent control than granular formulations. Factor (prodiamine) and Goal (oxyfluorfen) controlled bittercress for 8 months at 2× normal rates under nursery conditions of daily irrigation. Half-lives of Factor and Goal were 3 and 1 month, respectively. Extraction of herbicides from the gravel indicated that bittercress was controlled by 0.31 ppm of both herbicides.