JAPANESE KNOTWEED MONTH: time to spray

FOLIAR SPRAY YOUR KNOTWEED WHILE THE LEAVES ARE STILL GREEN AND THE PLANT IS SENDING SUGAR TO THE RHIZOMES.

4-5% GLYPHOSATE WITH ADDED SURFACTANT * is recommended for full effectiveness on this tough rhizomatous weed.  Follow all the directions on the package.  

What is important is that you treat after the plant has put out flowers and before the first hard frost.  IN OUR AREA, THAT IS SEPTEMBER UNTIL EARLY/MID OCTOBER.  Some people try to wait until the flowers drop.  Waiting for flower drop severely limits your available window for treatment.  

Plan to be treating your knotweed like this for a few years to eliminate it.

*Concentrated glyphosate/surfactant --original "RoundUp"--is not available at Home Depot, Lowe's big box stores.  Tractor Supply still sells it (as of this summer, anyway.)  Don't fall for the "RoundUp" branded products that Bayer sells.

REMEMBER THE DO'S AND DON'TS

DO: lop it short in summer to reduce size in fall. leave 1-2 nodes on stem, (~18-24”).  pile the cut parts on the site to dry out.

DO: foliar spray in in fall after flowering if you’re going to treat with herbicidee

DON’T: mow it (you’ll encourage branching underground)

DON’T: spread viable pieces

DON’T: spray it now. The leaves will turn brown and you’ll pat yourself on the back, and the underground reserves will not be affected. The stand will return as strong as ever.

For those of you who prefer repeated cuts to exhaust the plants; I’d like to hear how that’s working for you. Photos and an account of your progress would be extremely useful. email ashfordinvasiveplants@gmail.com