Japanese Hops
Identification:
Japanese hops are herbaceous annual vines that can grow up to 35 feet in a single growing season. They twine to climb adjacent vegetation and structures and sprawl across open ground to form dense mats several feet deep. Leaves have toothed edges and 5-7 lobes arranged palmately. They are opposite and approximately 2-6 inches long. Stems and leaves have hooked hairs. There are separate male and female plants. Both are greenish and produce flowers with five petals. Male flowers are arranged in airy cone-shaped clusters (panicles). Female flowers are arranged in short spikes. Japanese hops flowers in mid-late summer followed by seed production. Japanese hops reproduce by seed that can be dispersed by wind, water, wildlife, vehicles and equipment.
Control:
Repeated hand-pulling is an option to control small infestations. It is easiest to pull early in the season before the root system becomes established and extensive. Flowering stems or stems with seed should be bagged or burned. Protective clothing should be worn when handling Japanese hops because of its prickly hooked hairs. Repeated cutting with tools such as a weed-whip, brush-cutter, or mower is another option for controlling small infestations. Unfortunately, the vines re-grow quickly from cut stems so frequent cutting is necessary. The best time of year to mow is mid-May through July. Do not mow after seed set in the early fall because the mower will facilitate seed dispersal.
