Wow that says "higher than necessary hormone concentrations kill stem tissue".
I wonder if that's what happens with my klonex gel. In every case I have tried klonex the cutting has rotted.
I dip the cutting end in the gel let it sit for a few minutes, make a hole in the soil and put the cutting in without disturbing the gel.
I am batting 100% dead cuttings with klonex including kiwi, mulberry, figs and some green cuttings.
I have also tried a willow tea before by soaking the cutting overnight in the solution but I didn't notice any difference.
Maybe like the article says you need to pulverize the willow and boil it down first. Worth a try!