Common names: Red hailstone, Goldencreeper, Golden Creeper, Tuber Gourd, Wild Potato
Scientific name: Thladiantha dubia Bunge
Legal status: Prohibited Eradicate
All above and below ground parts of the plant must be destroyed. Additionally, no transportation, propagation, or sale of this plant is allowed. Failure to comply may result in an enforcement action by the county or local municipality.
Red hailstone is an attractive vine native to eastern Asia, southeastern Russia, northeastern China, and the Korean peninsula. Plant collectors began introducing red hailstone as an ornamental to European and North American gardens. Beginning in the 1930s, red hailstone was documented in a few states and Canadian provinces. The first documented occurrence in Minnesota was published in 1963 by a botany professor with Iowa State University. There were no new reports of this species in Minnesota until 2017. Since 2017, red hailstone has been documented in several counties.
- Red hailstone is an herbaceous perennial vine with separate male and female plants. To date, all plants reported in Minnesota are male, so there has not been reproduction by seed.
- Leaves are arranged alternately along stems. Curly tendrils are attached to the stem opposite leaves.
- Leaves are simple and heart shaped.
- Stems, leaves and leaf stalks are hairy.
- Flowering can occur from July to September. Flowers are yellow with five petals that fuse at the base to produce a tube. Male flowers have five short stamens (the pollen producing flower part). Female flowers have a three-part pistil, if pollinated, can mature into fruit.
- Vines die back to the ground each winter followed by rapid growth in the spring and summer. There are underground potato-like tubers that overwinter and sprout new growth in the spring.
- Both male and female plants are needed to produce fruits with seed. Fruits are oblong and up to 2 inches with brown seeds. Fruit color starts as green-yellow then matures to orange-red.
Vines grow over other vegetation in a wide range of habitats including natural areas, riparian areas, old fields, disturbed areas, transportation corridors, gardens, and crop fields. They can grow in light levels ranging from full sun to shade.
Means of spread and distribution
Both male and female plants are needed to reproduce sexually. Asexual reproduction is by tubers that form on underground stems. All plants found to date in Minnesota are male so there has not been reproduction by seed. Tubers float and can be moved along waterways. The largest infestation in Wisconsin is along the Big Green River.
Infestations are documented in Connecticut, Illinois, Massachusetts, Michigan, Minnesota, New Hampshire, New York, in the Canadian provinces of Manitoba, New Brunswick, Ontario, and Quebec. Escapes have also been documented in central and southeastern Europe and Japan.
Fast growing vines drape over other vegetation and can grow approximately 20 feet up into trees smothering the vegetation below them. At infestations in southwestern Wisconsin, vines have overgrown row crops and control by cultivation and registered agricultural herbicides were not effective.
Prevention and management
- Do not plant red hailstone.
- Once established, infestations are difficult to control because it is hard to kill all the underground tubers. Small infestations can be dug up. Repeated digging is necessary.
- Management recommendations are still in development. This species was not considered problematic until recently. The Renz Weed Science Lab at the University of Wisconsin Madison conducted an experiment for herbicide control. In summary, they recommended herbicide treatments with the active ingredient triclopyr in the summer and fall or a fall treatment with the active ingredient metsulfuron methyl.
- Persistence over multiple years is necessary to control established infestations.