1. Japanese knotweed Introduction DEREK WELLS What is it? What does it look like? Where did it come from? Where does it grow? Can it be killed? Do bugs kill it? Can it cause structural damage?

2. What does it look like? Green leaves with green and purple speckled hollow stems

3. What does it look like? Can grow to over 3 m high

4. What does it look like? Creates shade out competing most other plants.

5. What does it look like? Cane like stems

6. What does it look like? It dies back over winter leaving a carpet of dead stems

7. Where did it come from?  A plant brought to the UK as an ornamental in the mid 19 th Century.  There are 3 species of Japanese knotweed in the UK  1. Fallopia japonica – most widespread  2. Fallopia sachalinensis –giant knotweed  3. Fallopia x bohemica -hybrid

8. How and where does it grow?  It grows from vegetative propagation only mainly from Rhizome particles and it is said that stems can take root also.  It has the ability to grow from very small pieces and can grow in.  Most soil types  Most locations  Most water levels  Seeds are infertile.

9. Can it be killed?  YES-it is a plant it can be killed  Programmed spraying-using a Glyphosate based herbicide.  Stem injection using Glyphosate

10. Can it be killed?  Stem injection- is a method of injecting neat herbicide directly into the hollow stems of each plant.  This is best carried out during the flowering period (September-October).

11. Stem Injection

13. Stem Injection Trials 17 th September 2008

14. Stem Injection Trials 2 nd October 2008

15. Stem Injection Trials 13 th August 2009

16. Stem Injection Trials 7 th May 2010

18. Can it be killed?  Can I dig it out?  Dig and Dump is a recognised method, however disposal is very expensive as land fill tax in this situation is very high.

19. Do bugs kill it?  psyllid Aphalara itadori  A bug from Japan that lays eggs on knotweed leaves, grubs feed on leaves.  ‘Bug Trial’ still at early stages, results not proven as yet.

20. Structural Damage  It has been known for this plant to damage the structure of buildings  If allowed to get established it can exploit weak areas of built structures e.g. Cracks in brickwork, Foundations, Tarmac etc.