Evaluation of Soil Fumigants Applied by Drip Irrigation for Liatris Production

Cut-flower growers need alternatives to methyl bromide (MB) for pathogen and weed control. The efficacy of alternative chemicals applied by drip irrigation was tested in a cut-flower production system. In 2002, seven chemical formulations were tested: chloropicrin, iodomethane + chloropicrin, 1,3-dichloropropene + chloropicrin, sodium azide, metham sodium, furfural + allyl isothiocyanate, and furfural + metham sodium. In 2003, an additional treatment, dimethyl disulfide, was added. Most treatments reduced populations of Pythium ultimum and Fusarium oxysporum and increased stem height compared with the nontreated controls. Metham sodium, furfural + metham sodium, sodium azide, and chloropicrin significantly reduced incidence of Liatris stem rot caused by Sclerotinia sclerotiorum. Weed control was not acceptable either year for any treatments. Viable alternatives to MB for cut-flower production will require better treatments for weed control than was achieved in this study.