Knotweed is incredibly resilient, which means that you need to do more than simply cutting the stems to get rid of it. Even when the plant is totally cut back, the roots remain alive underground and will send up new shoots the following spring.
Sprayable herbicides are a good choice. Apply them late in the summer on a day without wind or rain. Wait for the weather to cooperate. Otherwise, any herbicide you apply will simply blow or wash away. A herbicide is only effective if it has enough time to penetrate the plant’s surface. It should be applied to as much of the plant as possible to encourage it to die more quickly. It usually will take anywhere from a week to a month to see results when using herbicides. You may need to reapply them to gain complete control- especially in areas where the knotweed is dense.
Weed wipers and stem injection methods are also effective at treating knotweed. These treatment techniques allow you to target specific plants with a high dose of herbicide. With sprayers, on the other hand, the herbicide has water added, which dilutes its strength.
Residual herbicides: Herbicides such as Picloram do a good job of limiting growth. They present some issues, however, when it comes to sensitive receptors or no-target vegetation. After treatment, the movement of the soil may also be restricted.
Systemic herbicides: Herbicides like glyphosate are absorbed through the leaves and translocate through the plant to the roots. Alternatively, they also can be absorbed from the surrounding soil via the roots. Once absorbed, they kill the entire plant including the shoots, leaves, and roots.
For treating the area more quickly, excavation is a good choice. Although it is more costly than using herbicide, it works well for large-scale weed removal. Contact the professionals at Environet. This is particularly true when the weeds need to be dealt with quickly. After the knotweed has been excavated, it can either be disposed of at the site or at a licensed facility that is located elsewhere. Any controlled burning of the knotweed should be done in the same area where it was removed. The ash from burning the plants can be used to amend the soil.
Research is currently ongoing into other treatment methods, including physical barriers, predatory insects and processing systems that treat the soil. As of right now, however, none of these methods have been widely adopted for treating this particular weed.