EFFECTS OF TRICLOPYR AMINE ON PURPLE LOOSESTRIFE AND NONTARGET WETLAND PLANTS IN SOUTH-EASTERN ONTARIO, CANADA

W e studied the effects of triclopyr amine, the triethylamine salt for mulation of triclopyr [[(3,4,6-trichloro-2-pyridinyl)oxy] acetic acid] on purple loosestrife (Lythrum rum salicaria L.) and non-target veget ation in a southern Ontario wetland during 1991 and 1992. Triclopyr wa s applied during bud to early bloom stage at rates of 4.0, 8.0 and 12. 0 kg/ha. During 1991, all treatment levels effectively controlled the aboveground portion of purple loosestrife. Grasses (family Gramineae) were unaffected during 1991, however, sedge species (Carer spp.) decli ned in numbers at higher treatment levels. At 1 year post-treatment, a dult purple loosestrife were not present in the 12.0 kg/ha treatment i ndicating that triclopyr effectively killed the root system, Seedlings dominated the total number of loosestrife plants in the 8.0 and 12.0 kg/ha treatment plots 1 year post-treatment. Sedges recovered in 1992 and grasses increased above 1991 levels. Removal of adult purple loose strife allowed more light to reach the substrate surface and created f avourable conditions for seed germination and plant growth, Triclopyr amine can effectively reduce adult loosestrife stem densities, however , additional herbicide applications may be required to prevent re-esta blishment through regeneration from the seed bank.