We evaluated herbicide treatments for control of umbrella dracaena, locally invasive in central Florida. Biannual treatments of imazapyr (3.2 and 6.4 g ai L−1), metsulfuron (0.08 and 0.16 g ai L−1), and imazapyr (0.8 g ai L−1) plus glyphosate (19.9 g ai L−1) reduced cover to < 3% at 12 mo, but no treatment eliminated the plant. In contrast, a single treatment on individual potted plants in greenhouse trials was highly effective with ≥ 98% necrosis/chlorosis at 6 mo and no regrowth at 9 mo posttreatment for most treatments. Management of umbrella dracaena will require more than two herbicide treatments with imazapyr, metsulfuron, glyphosate, or a combination of these herbicides if eradication is to be achieved. Because it is currently problematic and localized in one specific area in about 40 ha, it should be a high management priority before it spreads throughout Florida and possibly other states.
Nomenclature: Umbrella dracaena; Dianella ensifolia (L.) DC. (Hemerocallidaceae) DNLEN; also known as cerulean flax lily.
Interpretive Summary: In this study, we evaluated chemical control of umbrella dracaena (Dianella ensifolia), which is currently problematic in a single state park in Florida but is spreading outside the park. We found that two biannual spot treatments with imazapyr (3.2 g ai L−1) or metsulfuron (0.08 g ai L−1) reduced D. ensifolia cover to 1 and 3%, respectively, at 12 mo under field trials, but no treatment eliminated the plant. Although our results indicate two herbicide treatments will reduce D. ensifolia cover by > 97%, additional follow-up treatments will be required for long-term control of this plant in the park and to eliminate its spread outside the park. Because D. ensifolia is primarily localized in one specific 40-ha area of a state park, funding should be earmarked to eradicate this plant before it continues to spread to other natural areas in Florida and possibly other states.