IDENTIFICATION — This extremely invasive weed has simple medium-green leaves and spike-shaped pale-green to white flowers in summer. By the end of summer the plant can reach to 8 ft. tall.
FAVORITE CONDITIONS — Japanese knotweed spreads by rhizomes in full sun and dry soil. Cultivated areas, such as garden beds, and waste areas are where you’ll find this pest.
CONTROL — Use a nonselective herbicide like Roundup® as the plant is starting to go dormant in early fall.