PPDL Picture of the Week
February 17, 2020
JAPANESE HOPS (Humulus japonicus) An Invasive Weed of Indiana
Marcelo Zimmer, Weed Science
Department of Botany and Plant
Pathology, Purdue University
When one thinks of
hops they generally think of the beverage created from its cousin H. lupulus, but when a weed scientist
thinks of Japanese hops all they think about is trouble. Japanese hops is an aggressively growing perennial
vine that is considered an invasive plant in Indiana. It can often be found along ditches or creek
banks because of its affinity to moist soils.
This is also due to the fact that seeds are often dispersed by moving water. It does best in full sun to partial shade and
can sometimes be found infringing on pastures, roadsides, and open fields.
This vine has
simple, opposite leaves that are 2 to 4 inches long with 5 to 9 distinct
lobes. In most cases in Indiana, plants
have only 5 lobes. Leaves are on long
petioles (up to 8 inches in length) and have erose or toothed margins. The leaves are rough to the touch. There are bracts, small leaf like structures,
at the base of the petioles. Stems are
also rough to the touch due to down pointing hairs/prickles. Flowers are inconspicuous and green and are
born on leaf axils.
are mostly limited to hand pulling before the vines produce seed. However, spot applications of systemic
herbicides containing active ingredients such as metsulfuron or glyphosate were
shown to be the most effective at suppressing Japanese hops in trials from the
DNR in Maryland.
Always read and
follow all label directions when using herbicides.
Japanese Hops – Invasive Species Fact Sheet: https://www.in.gov/dnr/files/Japanese_Hops.pdf
Japanese Hop Images: https://www.weedimages.org/browse/subthumb.cfm?sub=10091
Managing Japanese Hops – What We Have Learned. https://dnr.maryland.gov/forests/Documents/jhopspresentation.pdf