Humulus japonicus
Japanese hop (Humulus japonicus) is an herbaceous annual vine. Native to eastern Asia, it was imported to the United States in the late 1800s for use in Asian medicine and as an ornamental vine. Within Missouri, Japanese hop is found most commonly in the Missouri and Mississippi river corridors, but it is increasing its range within certain floodplains. Japanese hop outcompetes established vegetation in sunny areas with exposed moist soil.
This sprawling, twining, climbing vine has opposite, palmately divided leaves that are rough to the touch. It has inconspicuous green flowers, with male and female flowers on separate plants. Female flowers are borne on a drooping cone-like structure with overlapping scales (called hops). The stems have short, sharp, downward-pointing prickles.
In areas with light infestation, manual removal can work well within moist soil in early spring when the root system is small. (You will need sturdy gloves to protect your skin from the prickles!) The entire root and plant must be removed and taken off-site to prevent regrowth. Repeated pulling should continue until dieback in fall when new plants cease to emerge.
In areas with heavier infestations, a pre-emergent herbicide containing sulfometuron methyl (Oust® XP) applied in mid-March generally causes minimal or no damage to other perennial vegetation, eliminating the need to rescue desirable vegetation from an established hop infestation. Application of a pre-emergent herbicide followed by a foliar application of glyphosate or metsulfuron applied prior to seed production (mid-April to August) may provide the most effective control. Subsequent applications will be necessary to control germinating plants throughout the season to prevent seed production.
See this Missouri Department of Conservation Japanese hop page for more information.
Identification and fact sheets
- Learn about Japanese hop at Invasive.org
- Learn more from the Missouri Department of Conservation about identification, threats, and control practices of Japanese hop
- Read Management of Invasive Plants & Pests of Illinois, a comprehensive guidebook with clear instructions on controlling many invasive plant species.
Representative photos of Japanese hop:
Japanese hop impact, abundance, and trend in Missouri
