Effects of vapours of chlorpropham and ethofumesate on wild plant species

Effects of vapours of two herbicides on plantlets of fourteen wild higher p lant species and two bryophytes were screened in fumigation experiments usi ng foliar injury, chlorophyll fluorescence and growth as response parameter s. After vaporisation of the herbicides for 48 h, concentrations in the cha mbers reached 77 mug m(-3) in the chlorpropham treatments and 184 ng m(-3) in the ethofumesate treatments. Despite the higher concentrations of the vo latile chlorpropham (vapour pressure, VP: 1.3 mP), plants showed no foliar injury, but vapours of this herbicide caused leaf crinkling in the agriophy te Agrostemma githago. The less volatile ethofumesate (VP: 0.56 mP) caused foliar injury in all higher species, with lowest no observed effect concent rations (NOECs) of 75 ng m(-3). Chlorpropham affected growth only in Agrost emma, while ethofumesate reduced growth in one third of the higher plant sp ecies. Chlorophyll fluorescence proved to be a less suitable response param eter compared to foliar injury and growth. No adverse effects were observed in mosses, probably due to the slow growth and hence small doses of herbic ides taken up. The extent of foliar injury due to ethofumesate showed a wea k positive relationship to relative growth rates and specific leaf area in the tested higher plant species. (C) 2001 Elsevier Science Ltd. All rights reserved.