Response of Monocotyledons to HOE 22870 and HOE 23408

Abstract

In the greenhouse, postemergence treatments of 1.12 kg/ha of HOE 22870 [4-(4′-chlorophenoxy)-phenoxy-α-propionic-isobutylester] or HOE 23408 methyl 2-[4-(2,4-dichlorophenoxy)phenoxy] propanoate were applied to three perennial weeds (two grasses and one sedge) and to 27 species or varieties of annual grasses (crops and weeds). The perennials were resistant to both compounds, but control of the seedling grasses ranged from 0 to 100%, indicating the potential of controlling certain grass weeds in certain grass crops, as well as in broadleaf crops. Generally, the response of a given species was similar for both compounds. However, on some grasses one compound was considerably more effective than the other. Seven species or varieties of foxtail (Setariaspp.) were treated with various rates of either compound. Differential responses were observed, but it appeared that all the foxtail species or varieties studied should probably be controllable with HOE 23408. All but yellow foxtail [Setaria lutescens(Weigel) Hubb.], should probably be controllable with HOE 22870.