CULT: Irises, daylilies and Stinger
One possibility, depending on how much space you have, is to take several
layers of newspaper or brown grocery bag paper, shield the irises and
daylilies next to the thistle, then take a solution of Round-up mixed for
hardwoods (somewhat stronger--perhaps by half--than mix proportions for soft
weeds) and put on a latex (or whatever) water-proof glove over which you pull
on a soft cotton glove, dip your hand into the mix and *wipe* the mix on the
Canadian thistle. Or perhaps better yet, get some sponge brushes--about four
inch size or somewhat smaller and paint the plants. Just don't get even tiny
amounts on the ornamentals.
If the thistle is growing up inside your clumps, you need to dig and divide,
being extra careful not to transplant any underground stems of the thistle.
I'm sure I don't have to alert you to the problems you face if the thistle
blooms and goes to seed. You might look over the fence at the surrounding
properties. The thistle came from *somewhere.*
I know--the spines are awful. You might consider hoeing out the growing
plants and wait until the sprouts are six inches or so tall, then treat them.
Young, tender growth is more absorbant of the herbicide. You will have to
repeat the procedure, perhaps several times over the remainder of the season.
The root systems of Canadian thistle go deep and also form incredible mats.
You may even have some show back up next year.
I'd be tempted to move all the plants you want to save and simply spray, over
and over at about three week intervals, the Canadian until you kill it. The
lethal effect needs time to work. It may be some time before you know if you
did the thistle much harm or not.
The normal dilution might never get them. That's why I'm suggesting the
"woody plants" dilution from the concentrate. If you do spray, it is safest
to use the hand squirt bottle with a stream, not a spray, and squirt gently
from close up. You don't want to get any drift on your ornamentals--at all.
I have killed Canadian thistle with 2,4D and/or 2,4,5T or TP, I don't remember
which, but I don't think you can get these easily anymore, if at all. They
tend to contain tiny contamination amounts of Dioxin. The newer herbicides
are safer--for us.
Best of luck! Keep us posted on your progress.
Neil Mogensen zone 7 in western NC
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