Managing land infested by Japanese knotweed in a timely and appropriate way can avoid:
? excessive cost
? potential prosecution and/or compensation claims
? physical damage to buildings and hard surfaces
? harm to the environment.

The most effective time to apply glyphosate is from July to September (or before cold weather causes leaves to discolour and fall). Spring treatment is acceptable, but less effective. Triclopyr, picloram and 2,4-D amine can be used throughout the growing season. You should avoid the flowering period to protect bees and other pollinating insects. The majority of herbicides are not effective during the winter dormant stage because they require living foliage to take up the active ingredient. An exception to this rule is picloram, which can be applied as a soil treatment.