The spreading of giant knotweed mustbe prevented and adverse effects limited as cost-effectively as possible. It is necessary to eradicate existing vegetation that has spread to nature, especially in nature reserves and their vicinity, as well as in populated areas and in the vicinity of roads.

Spreading to new sites must be prevented and special care must be taken not to move soil containing fragments of ground stems or roots to new areas. In addition, special care must be taken in the treatment of plant waste to prevent the spreading. To control bulky knotweeds, it is recommended to primarily use mechanical control methods.

Large knotweeds can be very difficult to eradicate due to the deep roots and it requires perseverance and several years of work. When the plant is still small, the seedlings can be pulled out of the ground by hand, along with the roots. The growth power of the rhizome can be weakened by repeatedly cutting the vegetation off. Simply destroying the above-ground parts, even repeatedly, may not always be enough to destroy the entire vegetation. Small growths may be eradicated by first cutting the plants down completely and then covering the area with black plastic for 3-4 years.

The following method has been successfully used to control knotweeds: the stems are cut off near the base and the hollow stems are sprayed with a pesticide. This is repeated a few times a year until the vegetation disappears. In difficult locations, you may have to resort to pesticides. They should not be used at all in groundwater areas, near wells or surface water, or near children's playgrounds. Always, it is a good idea to monitor the plants for several years after the control measures, and remove all possible emerging shoots by hand.

Special care must be taken when disposing of plant waste and soil containing large knotweeds. Knotweeds do not spread from stems or leaves, so they can be composted or left in place to decompose. Instead, rhizomes or parts of roots must not be placed in compost, as they may not be destroyed by composting, and there is a risk of spreading of the plant along with the compost soil. It is possible to dispose of small amounts of plant waste or soil containing fragments of root or rhizome with mixed combusable waste.

Giant knotweed (jättitatar?) – Reynoutria sachalinensis

Giant knotweed (
jättitatar
?
) – Reynoutria sachalinensis