Hedychium gardnerianum Sheppard ex Ker Gawl.

Code

HEYGA

Hedychium gardnerianum is a vivacious rhizomatous herbaceous plant that multiplies abundantly by branching its rhizomes. Any underground part, even small, is capable of regenerating a new individual. It also produces many seeds that are spread over long distances by birds and rats.

omparison table for Hedychium
 

India: Hedychium gardnerianum grows in cool mountainous regions at an altitude of 1200-2500 m, with a subtropical climate, cool winters and mild summers. It is present in forests and wooded areas as an undergrowth species. It has been introduced into gardens as an ornamental plant and has escaped from these outbreaks, especially along roads and stream banks. It is also a weed of natural forests, ravine edges, railroads and roads, as well as wetlands and wastelands.
Reunion Island: Very frequent and abundant invasive species in the undergrowth, along roads and paths and along gullies at medium and high altitudes, from 800 to 2500 m. Very ubiquitous species, it appreciates deep and humid soils.

 

Global harmfulness

Hedychium gardnerianum is essentially an invasive species for natural or cultivated forestry environments. It represents a strong threat to biodiversity, particularly plant biodiversity.

Local harmfulness

Reunion: Hedychium gardnerianum is not considered a crop weed, although it can be found on the edges of plots from 800 m altitude. It is mainly an invasive species of natural environments (forests, gullies) and degraded or anthropized environments.
South Africa: Hedychium gardnerianum competes with and replaces native species and obstructs access to plantations.

Global control

Mechanical control

Mechanical control of Hedychium gardnerianum by pulling out rhizomes can only be envisaged on very small and recently colonized areas. Cutting the flowering stems before seed production only slows down the spread of the plant.

Chemical control

Metsulfuron appears to be the most effective herbicide against this species, sprayed on leaves, stems and visible rhizomes. Plant death occurs 3 months after treatment. Concentrated glyphosate can also be used as a spot spray on sections of stems that have been previously cut just at the rhizomes.

Biological control

Strains of Ralstonia solanacearum from Hawaii have been shown to be effective in significantly affecting Hedychium gardnerianum and appear more or less selective for other Zingiberaceae. To date the risks of conflict of interest have not allowed to implement this type of control in the wild.

Herbarium pictures ReCOLNAT: https://explore.recolnat.org/search/botanique/simplequery=Hedychium%2520gardnerianum