Efficacy and Cost of Selected Herbicides for Control of Skunkvine (Paederia foetida)

Skunkvine (Paederia foetida) is a fast-growing, woody vine that is native to eastern and southern Asia. In the late 19^th century, skunkvine was introduced into Florida as a potential fiber crop and quickly escaped cultivation and began invading natural areas throughout the state. By 1993, skunkvine was labeled a Category 1 species by the Florida Exotic Pest Plant Council and declared legally noxious in 1999. It has been documented in at least 25 counties in Florida and is a common nuisance in landscapes, agricultural production, and natural areas. Despite its prevalence, little information on herbicide efficacy exists. Herbicide dose-response trials were initiated at the Mid-Florida Research and Education Center in Apopka, FL to determine the effectiveness of seven different herbicides to three stages of skunkvine; juvenile (green, softwood, immature foliage, 12 to 24 inches in height.), mature (mostly hardwood, mature foliage, 24 to 48 inches in height), and established (mostly hardwood, 48 to 72 inches or more height). Skunkvine were grown in 3.8 L nursery pots filled with a standard pinebark:peat substrate and were kept inside a greenhouse. On the day of treatment, all plants were removed from the greenhouse and herbicides were applied with a CO₂ backprack sprayer calibrated to deliver 25 gallons per acre. Herbicides applied included triclopyr amine, triclopyr ester, glyphosate, imazapic, aminopyralid, fluroxypyr, and aminocyclopyrachlor. Each herbicide was applied at 0.125. 0.25. 0.5, and 1.0 × its highest label rate. Data collected included visual control ratings at 1, 2, and 3 months after treatment (MAT) and shoot fresh weights at 3 MAT. Results showed that across all rates tested, triclopyr ester provided the most effective control of skunkvine at all three growth stages. Other herbicides including triclopyr amine, glyphosate, aminopyralid, fluroxypyr, and aminocyclopyrachlor also provided effective control but typically only at the highest label rate.