Published April 1963. Facts and recommendations in this publication may no longer be valid. Please look for up-to-date information in the OSU Extension Catalog: http://extension.oregonstate.edu/catalog
Woody knotweeds are listed as noxious weeds throughout most of the United States. This publication briefly describes the characteristics and biology of four species of woody knotweeds and summarizes management and control options. Intended for home gardeners and small-acreage landowners.
Knotweeds are a group of closely related invasive plants from Asia. Knotweeds are very tall plants that can grow to over three meters with bamboo-like hollow stems and heart-shaped or lance-shaped leaves. They spread quickly and form tall, dense thickets. They dominate stream banks, sides of roads, gardens, and other...
Japanese and giant knotweeds were introduced to North America in the late 1800s as ornamentals but soon escaped into the wild. They are particularly invasive along streams, roadsides, and waste areas. Large, spreading patches of knotweed can completely dominate and displace native species in open sunlight. Erosion can increase on...