#RussianKnapweed is controlled by picolinic acids (e.g., aminopyralids, clopyralids) and… not much else. I keep threatening to get my permit so that I can use picloram, because a small amount of that will do better with less environmental impact than year-on-year treatment with just about anything else.
(Cue everyone showing up in my mentions to tell me how bad glyphosate/roundup is… now).
#Thistles can be controlled with picolinic acids or dicamba.
Finished what I hope will be the last #pesticide application in the southern pasture for the rest of the year. I need to do one last pass for hemp dogbane, but I think I got all of the #RussianKnapweed.
The goal here is that it will take the pesticide down into its root system over winter and then we'll have a lot less of it to deal with next year.
Like nothing else I deal with, the #RussianKnapweed feels like a corruption or a sickness in the land.
It almost certainly doesn't feel that way if you are in its native range, but where I am it feels… wrong in a way that is hard to explain.
I know where it is growing because nothing else grows there. It poisons the ground. It grows where the soil is disturbed, it takes advantage of adverse conditions such as fire.
One more round of spraying today now that the weather has cooled off for a day. I found a fully adult patch of it that had been hiding from me and was just barely on this side of when chemical control is most effective.
I continue to go out with my soil knife every day and cut out the small offshoots I'm finding, mostly in areas where it was mowed or sprayed with just weedmaster (2,4D+dicamba)—basically areas where just the top growth was killed or cut.
One phenomena in #IntegratedPestManagement for weeds I've been reading about and recognizing in my own rehabilitation project is the phenomena of killing the top growth of the weed but not the root itself.
This is evidently a known issue for dicamba and glyphosate on weeds like #RussianKnapweed.
Basically you can kill off the top part of the plant, but the roots will continue and happily try again either later in the season or next year.
I've seen what I suspect is this a few times on #RussianKnapweed if I treat with just dicamba and/or glyphosate, but I don't seem to have that problem with Chaparral.
But for the annuals and even some of the other perennials this isn't an issue. Hit them at the right time and dicamba or glyphosate will work just fine.
So far, again anecdotally and with some assumptions about what I'm seeing:
2,4D + Dicamba is the best I've got at killing the #RussianKnapweed top growth.
Chaparral is best for long-term control, but doesn't always control the top growth this year adequately. Seems to do best when combined with 2,4D.
Glyphosate works well on other weeds but is basically useless on the knapweed even if you hit at the right time. You can kill the top growth sometimes but it's almost easier to just hand weed.
The one on the top/left is a small knapweed plant… without the entire root. The one on the right is kochia. The kochia's root system doesn't get a lot bigger than that: the only time you find them bigger is on much bigger plants and even then proportionally they don't grow nearly as quickly.
Kochia is an annual. It dies off every year and comes back the next. Knapweed is a perennial that can have a 20+ foot root system.
The battle against the #RussianKnapweed continues. Every time I think I have hit it all I find more. Sometimes it was just something I missed. Sometimes it is new growth.
I've hand-pulled a few of the new growth areas, but there's only so much that can be done there. Most of the rest of it gets sprayed with 2,4-D, Dicamba, and/or Chaparral. Plant at a time.
On the plus side I can see successful galls developing on the plants I put the wasps next to, so hopefully that'll help going forward.