Are there any organic controls for poison hemlock in pastures?
R.M. TennesseeAnswer: Several western states have excellent publications on poison hemlock, Conium maculatum. The Montana publication (see Resources, below) includes distinguishing characteristics so that you can positively identify the weed and tell it from similar plants. Note the sections on managing the weed population, including mechanical and biological control methods.Another fact sheet from Arizona contains a few more bits of information about the plant and its control. This fact sheet doesn’t mention the hemlock moth, Agonopterix alstroemeriana (Clerck), which offers some, though not always excellent, control. There are two sources of the moth listed below, if you decide to purchase some as a part of your organic control program.You may also want to see the ATTRA publications on flame weeding. This is another type of mechanical control that should prove effective if well-timed and consistently used. ResourcesDiver, Steve. 2002. Flame Weeding for Vegetable Crops. ATTRA Publication. National Center for Appropriate Technology, Fayetteville, AR. 16 p.Moser, L., and D. Crisp. No date. Poison Hemlock: Conium maculatum. San Francisco Peaks Weed Management Area fact sheet. Coconino National Forest. 2 p. www.usgs.nau.edu/swepic/factsheets/coma2sf_info.pdf (PDF 161 kb) Pokorny, Monica L., and Roger L. Sheley. 2000. Poison Hemlock. Montguide MT 2000-13. Montana State University Extension Service, Bozeman, MT. 4 p. www.montana.edu/wwwpb/pubs/mt200013.htmlSullivan, Preston. 2001. Flame Weeding for Agronomic Crops. ATTRA Publication. National Center for Appropriate Technology, Fayetteville, AR. 2 p.Sources of hemlock moth Agonopterix alstroemeriana (Clerck): Integrated Weed Controlwww.integratedweedcontrol.com/hemlock.htm Biological Control of Weeds, Inc. www.bio-control.com/7j.asp