Preventing establishment of exotic shrubs (Cytisus scoparius (L.) Link. and Cytisus striatus (Hill)) with soil active herbicides (hexazinone, sulfometuron, and metsulfuron)

Abstract

A greenhouse study was conducted evaluating the potential for commonly used forestry herbicides to control germination success of Scotch broom (Cytisus scoparius (L.) Link.) and Portuguese broom (Cytisus striatus (Hill). Three herbicides, hexazinone, sulfometuron and metsulfuron, were evaluated at six rates encompassing normal rates used for herbaceous weed control. The data suggest that these herbicides applied prior to establishment can strongly affect seedling establishment of these species even though they are ineffective on mature individuals. Hexazinone strongly affected both the final weight of surviving seedlings and the probability of seedlings from broom species to survive to week nine. Sulfometuron had no effect on survival probability of either species but reduced final dry weight and delayed true leaf development at increased rates. Metsulfuron reduced the survivorship potential of Scotch broom but not Portugese broom. Final dry weight decreased and development of true leaves was delayed for both species treated with metsulfuron. These results suggest that preemergence treatments with hexazinone may provide an effective method of preventing broom establishment. Sulfometuron and metsulfuron were not as effective at preventing successful establishment as hexazinone.