Titi (Cyrilla racemiflora L.) is a vigorous native shrub or small tree occurring in poorly drained sites of the southeastern Coastal Plain. If unchecked, it forms dense thickets inhibiting herbaceous forb cover in ephemeral wetlands, leading to habitat degradation for rare and endangered amphibians such as the flatwoods salamander and bog frog. Thus, controlling the spread of titi is critical to restoring and maintaining these habitats. Herbicides that translocate and can get to the root mat of titi, such as glyphosate (Rodeo), imazapyr (Habitat), and triclopyr (Garlon 3A) could be effective at controlling this species. In, 2018, we initiated four uniform replicated field studies at two sites in the Florida Panhandle to compare the efficacy of (1) selective herbicides (Rodeo, Habitat, Garlon 3A), applied alone or in mixes of different concentrations, with or without adjuvant, and (2) application methods (foliar spray, cut-stump, cut-stem), in controlling titi. All the study treatments at both sites were replicated 10 times (10 rootstocks), including non-treated controls. One year after treatment, we (1) measured percent titi control and (2) assessed herbicide injury to non-target vegetation, also noting injury to plants important to ephemeral wetland-breeding amphibians.
Results/Conclusions
For foliar applications, Rodeo alone (5%, 7.5%, 10%) or in combination with Habitat at all three rates (7.5% + 1%, 7.5% + 2%, 7.5% + 3%) were very effective, resulting in 76 to 100% control across sites. The most effective treatments for cut-stump treatment were Garlon 3A (90-99% control), Habitat alone (71-100%), and the combination of Habitat and Rodeo herbicides (71-100%). Rodeo alone was least effective at both sites (37-79%), but the effectiveness varied. Cut-stem (hack and squirt) applications were very effective across all herbicide treatments, ranging from 85-100% control. Across all treatments, about half of the plots with critical species present showed a reduction in critical grass species (bunch grasses such as Aristida spp., Rhynchospora spp, Dicanthelium spp., etc.). Reduction in critical forb species (Eriocolonsp., Xyris spp., Lobilia floridana, Helenium pinnatifidum, etc.) was only noted in the low rate of combination treatments of Rodeo and Habitat. Garlon 3A showed the least reduction for plants deemed as critical species.