Skunk-vine (Paederia foetida L.) is an invasive vine native to eastern and southern Asia and is widely distributed in Florida, Hawaii, and other southeastern U.S. states; however, little research has focused on herbicide control. Greenhouse and field experiments were conducted to determine efficacy of aminocyclopyrachlor, aminopyralid, fluroxypyr, glyphosate, imazapic, triclopyr amine, and triclopyr ester at low and high labeled rates when foliar applied to P. foetida at various growth stages in greenhouse experiments. Longer-term control was evaluated in field experiments in central Florida using the same herbicides. PRE herbicides labeled for use in landscape plantings, including dimethenamid-P, flumioxazin, indaziflam, isoxaben, and prodiamine, were also evaluated in greenhouse trials by seeding containers with P. foetida seed. In greenhouse experiments, POST herbicides, including aminocyclopyrachlor, aminopyralid, glyphosate, both triclopyr formulations, and the high rate of fluroxypyr (0.24 kg ae ha−1), provided >90% control across all growth stages at 4 mo after treatment with no regrowth observed. Imazapic provided 49% to 89% control, with efficacy decreasing with P. foetida size, and generally provided less control than other treatments. Field experiments confirmed results from greenhouse studies. In PRE trials, flumioxazin and prodiamine provided better control than all other PRE herbicides evaluated, reducing shoot weights by 99% and 84%, respectively, compared with nontreated controls. Our data suggest all herbicides evaluated POST could potentially be used to manage P. foetida, although less control was achieved with imazapic compared with other herbicides. Further research is needed to determine herbicide efficacy on more mature plants and to develop application methods that would be less injurious to non-target vegetation. In landscapes, flumioxazin or prodiamine could be used for PRE control, but POST options that are labeled for landscape use should be identified in future research.

Cogongrass [Imperata cylindrica (L.) Beauv.] is an invasive grass in the southeastern United States, and its impacts strongly affect the region, especially Florida. Herbicide strategies have been limited to glyphosate in natural areas and imazapyr in managed pine forests and non-crop areas where its soil residual activity is of less concern. This lack of options has raised concern for herbicide resistance, which has never been documented for I. cylindrica. Land managers have also reported variable I. cylindrica control, especially with glyphosate. To determine whether herbicide resistance was a possible explanation, we examined glyphosate response of I. cylindrica from 12 Florida populations. We also tested aminocyclopyrachlor with and without glyphosate and flumioxazin with glyphosate. Results indicated that herbicide performance was similar across I. cylindrica populations: glyphosate and aminocyclopyrachlor reduced I. cylindrica biomass by 78% and 76%, respectively, and the combined tank mix reduced cogongrass biomass by 91%. Flumioxazin tank mixed with glyphosate did not improve control compared with glyphosate alone. There were no differences in pretreatment I. cylindrica shoot height, with the exception of two panhandle populations that were shorter. Subsequent harvests indicated few differences in shoot and root plus rhizome weights among untreated controls for almost all populations, with the exception of one of the initially shorter panhandle populations. Our findings indicate that variability in glyphosate efficacy, as suggested by managers, is unlikely due to any conferred resistance. Other abiotic factors such as drought and shade and applicator factors such as carrier water quality should be examined to better understand this issue. Additional studies examining non-target impacts of aminocyclopyrachlor should be conducted to determine its potential fit into I. cylindrica management.

Since its introduction to the United States in 1852, Chinese privet (Ligustrum sinense Lour.) has spread throughout the Southeast, invading many natural areas. Manual control by cutting or shredding is one of the most common strategies many land managers employ. However, rapid sprouting from the root collar and lateral roots commonly results in poor control. Cutting followed by either glyphosate or triclopyr application to the stumps is generally effective, but the efficacy of these herbicides in relation to treatment timing and L. sinense root collar diameter has not been evaluated. The objective of this experiment was to determine the effectiveness of glyphosate and triclopyr cut stump treatments compared with cutting alone at spring and fall timings across a range of L. sinense size classes. Studies were conducted at two locations in Auburn, AL. Treatments included cut stump+no herbicide, cut stump+ glyphosate (120 g L−1), or cut stump+triclopyr (90 g L−1). Treatments were applied to at least 50 experimental units each at April and November timings. Root collar diameter was recorded for each stem, stems were cut 2.5 cm above the ground, and herbicide treatments were applied within 30 s. Ligustrum sinense mortality and sprouting were quantified 6, 12, and 18 mo after treatment. Both glyphosate and triclopyr amine were very effective in controlling L. sinense at both spring and fall timings. However, glyphosate provided slightly better results than triclopyr when lateral sprouting was included. Application timing also was significant, with a lower percentage of sprouting following November treatments than April treatments. Stem size influenced treatment success, as larger stumps tended to sprout more than smaller stumps. These results indicate L. sinense can be controlled with cut stump herbicide treatment using either glyphosate or triclopyr with spring or fall timings at concentrations much lower than typically used.