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Hi all,

Well this is new. I was called to conduct a site visit for initial treatment by a woman in the city of Marquette who has knotweed. She has last year's growth still standing, so we were going to look at it this year to determine the next steps for first-time treatment for her. Upon arriving at the site, there's definitely knotweed, but nothing new growing this year. I'm stumped. I've never seen knotweed take care of itself, but she's been living in the house for 35 years, with the knotweed there for only about 4-5 years until she had someone ID it for her last year - so this year would have been the first treatment. Other knotweed sites in the UP are already at 4 feet of growth, if not more dependent on the site location, and this doesn't even have sprouts.

Any ideas? Other than aliens or divine intervention? Has anyone else encountered knotweed that limited its own growth somehow?

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That's crazy! I've heard in some cases that knotweed will "retreat" if it faces a large stress, not sprouting for a year or two. Could this have been the case? However, the only cases I've seen this in were really harsh mid-spring freezes, and after treatment. Unfortunately, the knotweed usually springs back up a few years later, sometimes a short distance away. Has anyone else seen this happen? 

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I have not seen in personally but I know that it is wise to assume that it might come back. Just as Nor said, a strong stressor can cause a temporary retreat for a year or two (there are reports of a three year retreat in the UK).  I would also inspect last years growth for signs of infection that may have aided. Or Perhaps someone came in and treated without the homeowner knowing? This is interesting indeed. Studying the oddballs are always interesting and sometimes key to finding new tactics. Please keep us posted!

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I'm not sure that this stand would follow some of the necessary conditions for a "retreat" - though that's something I actually hadn't heard of yet! We have no record of treatment here through the CISMA, and she still maintains that she's never given any permission for treatment to another entity. I hope there's not rogue treatments happening, that's not cool!

I've let her know to keep me posted and if/when any sprouts come up to give me a ring, so we're keeping an eye on it. Still fascinating to see!

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