Japanese Knotweed

Several years ago I noticed a rather large out-of-control weed growing in the garden which I later identified as Japanese Knotweed. For the last three years I have been trying to tackle it but with no success. Two years ago I tried cutting it down hoping it would give up and die. This didn't work. Last year I covered all the affected area with large amounts of Ammonium Sulfamate & Sodium Chlorate. This killed off everything in the area, even killing off the knotweed.

This year its back for revenge with several stems already two foot high. So far I have cut down the small weak stems only leaving the large ones. I have injected these with large amounts of Ammonium Sulfamate directly into the stems. I also cut off all the leaves to prevent it from getting sun light. Is this method likely to kill off the roots? I would like your advice on how to kill this beast.

I don't know if these are connected but I have a hugh amount of ground weeds growing amount the Knotweed. I am not sure what these are but they have very thick root which tunnel everywhere. I though it was knotweed at first but there are too many leaves on them and its too small. Any ideas?

 

Glyphosate, which is takem up by the leaves and goes right into the roots. There is now a brand that says its suitable to knotweed. It will give advice on when and how to apply - dont cut down anymore stems until you get this product.

 

Hi Andyh. i see you have a huge problem there. you are dealing with a " BIG BEAST". this stuff can survive temps of -35 can extend 23 ft horizontally and 9 ft deep ,almost impossible to remove by digging .my information is removal requires a weedkiller Glyphosate or 2,4-D. that is the good news. the bad news ,this repeated treatment should work over a 3 yr period. personally i would get a professional in to do the job .as far as i can gather it has to be removed in poly liners as any part of the roots system dropped accidently into the soil again ,re root . all the best mate
music.

 

You could also try your local council. I think they offer help in eradicating this nuisance.:wink: