Before the new growth pushes up through the soil the canes in early Spring really do look like a rather dead brown mass.
The trouble is that the power is all stored in the rhizome – underground, occasionally with a crown protruding. So as soon as the weather warms the plant will grow away at an extraordinary speed.
Here are some images to help in your identification:
Should you be wanting to start a building project it is possible to eradicate the plant before it starts to grow – ie now, through the Dig Out method.
If this should be of interest please get in touch.
As I am sure you know we have a great button on the home page that will take you to lots of images of Japanese knotweed throughout the year.