The Effect of Hexazinone, Sulfometuron, Metsulfuron, and Atrazine on the Germination Success of Selected Ceanothus and Rubus Species

Abstract

Abstract This study documents the impact pre-emergent forestry herbicides have on germination of some selected seral woody competitors in the Pacific Northwest. Four commonly used pre-emergent soil-active herbicides (hexazinone, sulfometuron, metsulfuron, and atrazine) typically used for herbaceous weed control were applied at six rates over stratified seed of Ceanothus velutinus (CEVE) and Ceanothus integerrimus (CEIN) in a greenhouse efficacy trial. In addition, hexazinone and sulfometuron were applied over stratified Rubus ursinus (RUUR) and Rubus parviflorus (RUPA) seed and sulfometuron over stratified seed of Rubus spectabilis (RUSP) at the same six rates. Numbers of seed to successfully germinate and develop true leaves were counted over a 9 wk period immediately following herbicide application. The hexazinone treatments reduced germination and growth of CEVE, CEIN, and RUPA. The RUUR species was tolerant of the hexazinone herbicide at low rates but at higher rates was strongly affected. The sulfometuron treatments had less effect on survival probability than hexazinone but strongly reduced the average dry weight of plantlets of all species. Seedling dry weight decreased with increasing rate of both metsulfuron and atrazine. Increasing the metsulfuron rate reduced the probability for CEVE seedlings to survive but not CEIN. Finally, atrazine sharply reduced the plantlet survival and reduced dry weight of both CEVE and CEIN even at low rates.West. J. Appl. For. 17(4):194–201.