After discovering knotweed in one of my customers garden I did some research on this much maligned plant to discover it is potentially rather good for you due to its high resveratrol content. Infact all the reveratrol suppliments seem to be made from this and not grape vines like the marketing would suggest.
As I had been making other weed sprays and typically they were usually medicinal too. I searched for the potential of this plant too and eventually found the following:
Knotweed extract "induces phytoalexins which infer resistance to powdery mildew and other diseases such as Botrytis". In other words, the extract helps the crop or ornamental plant fight the mold rather than attacking the mold directly. If the extract were made with organic alcohol, the fungicide should be considered organic.
Knotweed is also edible. The young shoots taste like rhubarb. At the right time and conditions, it's a food plant! I would be interested to hear about your experiment with it as a fungicide. Are you going to experiment?
Yes, it was thankfully not too well established and I might have set it back a bit by weeding it too well! So I am just waiting for it to come back first.
I also weeded a lot of ground elder and bindweed from other customers houses. The ground elder has been in a container without light for over 6-8 months now and its still trying to grow! Again that is edible and medicinal and clearly a strong plant so I think that could also make for an interesting spray/feed.
please buy my thing and then I'll have more money: