Miller, James H.; Manning, Steven T.; Enloe, Stephen F. 2010. A management guide for invasive plants in southern forests. Gen. Tech. Rep. SRS–131. Asheville, NC: U.S. Department of Agriculture Forest Service, Southern Research Station. 120 p.
Princesstree or paulownia [Paulownia tomentosa (Thunb.) Siebold & Zucc. ex Steud.] is a deciduous tree to 60 feet (18 m) tall with large heart-shaped leaves that are fuzzy hairy on both surfaces. Before leaves appear in spring, trees are covered with showy pale-violet flowers that yield persistent pecanlike capsules in clusters during fall and winter. Each capsule splits to release thousands of tiny winged seeds that are spread by wind, water, and gravity. Abundant flower buds are present on erect stalks over winter. Viable seed can be produced by 5- and 7-year-old plants. In the mountains, seed can be dispersed by wind up to 2 miles (3 km) away. Invades widely after fire, harvesting, and other disturbances. Forms colonies from prolific root sprouts. Still widely sold and planted as an “instant” shade tree as royal paulownia or royal empress.
Management strategies
- Do not plant. Remove prior plantings, and control sprouts and seedlings. Bag and dispose of plants and capsules in a dumpster or burn.
- Minimize disturbance within miles of where this plant occurs.
- Treat when new plants are young to prevent seed formation.
- Cut when fruit are not present.
- Manually pull new seedlings and tree wrench saplings when soil is moist, ensuring removal of all roots.
- Burning treatments are suspected of having minimal topkill effect due to scant litter.
Recommended control procedures
Large trees. Make stem injections using Arsenal AC* or when safety to surrounding vegetation is desired, Garlon 3A or a glyphosate herbicide in dilutions and cut-spacings specified on the herbicide label (anytime except March and April). For felled trees, apply these herbicides to stump tops immediately after cutting. Also, ORTHO Brush-B-Gon, Enforcer Brush Killer, and Vine-X are effective undiluted for treating cut-stumps and available in retail garden stores (safe to surrounding plants).
Saplings. Apply a basal spray of Garlon 4 as a 20-percent solution (5 pints per 3-gallon mix) in a labeled basal oil product, or apply undiluted Pathfinder II when safety to surrounding vegetation is desired. Elsewhere, apply Stalker* as a 6- to 9-percent solution (1.5 to 2 pints per 3-gallon mix) in a labeled basal oil product, vegetable oil, kerosene, or diesel fuel (where permitted).
Resprouts and seedlings. Thoroughly wet all leaves with one of the following herbicides in water with a surfactant (July to October): Arsenal AC* as a 0.75-percent solution (3 ounces per 3-galllon mix); Arsenal PowerLine* as a 1.5-percent solution (6 ounces per 3-gallon mix); or when safety to surrounding vegetation is desired, a glyphosate herbicide, Garlon 3A, or Garlon 4 as a 2-percent solution (8 ounces per 3-gallon mix).
* Nontarget plants may be killed or injured by root uptake.
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