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Hi all,

Has anyone done DNA tests on knotweed to determine whether it is Japanese, Bohemian or Giant? I'm working with an Oakland University professor on this and just curious if anyone has tried it before in Michigan. Let me know if so!

Also curious once we determine which varieties are present in our area whether the treatment effectiveness may vary depending on the variety. Any insights appreciated, thanks!

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No DNA tests that I know of in Michigan, but I was very heartened by a study shared at UMISC last year.  Presented by John Gaskin (et al.) of the USDA and focusing on knotweed populations in the Pacific Northwest, the nutshell was that managers are pretty darn good at IDing the difference between Japanese, giant, and Bohemian knotweeds.  He had folks send in samples and their guesses, and I don't remember the exact error rate, but it was REALLY low, to the point where he joked, "I guess you guys know your stuff!"  Other people named in the study included Mark Schwarzlaender (U Idaho), Fritzi Grevstad (Oregon SU), Marijka Haverhals (U Idaho), Rober Bourchier (Ag & AgriFood Canada), and Timothy Miller (Washington SU).

We have mainly Bohemian and giant knotweed (though I expect we'll find that we do have SOME Japanese if we look more closely) here in ISN's area, and we haven't noticed much of a difference in efficacy; they all die well in the first year of treatment (50-90%), then hang on bit by bit for the next few years, like mean jerks.  I think this may be very different for the biocontrol study, however.

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Thanks, Katie! We're going to do at least some initial tests for Michigan to confirm the types we have. The DNA tests might also be able to tell us how many separate introductions/populations there are, which might be helpful. 

I'm hoping we can have this straightened out soon so that we would be able to verify the correct variety for anyone participating in the biocontrol study. 

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