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Here's a quick overview of the treatments ISN has found most successful for controlling knotweeds: Milestone (aminopyralid) Faster kill (~3 years), more off-target effects Standard rate (3-7 oz/acre; 0.01%) Using nonionic surfactant (standard rate) Late spring (3-4 ft high) or late summer (at least 60 days before frost) When treating in late summer, it is helpful to do a cut of the plants a month or so in advance ONLY IF safe disposal of the stems is possible At some sites, repeat treatments (spring & summer) may be appropriate, so long as maximum application rates are not reached Not aquatic approved Note: Tree sensitivity issues--some trees will die if their roots mingle with knotweed that is treated with Milestone. Clearcast (imazamox) Acceptable kill (~5 years), fewer off-target effects Cocktail: 5% Clearcast 1-2% Methylated Seed Oil (MSO) Not all MSOs are aquatic-approved!! Check before applying to knotweed in areas with standing water 1-2% glyphosate (aquatic-approved formulation) Best sprayed in late summer/early fall Spraying at least 60 days before the first frost is CRUCIAL--this date will vary by location (for northwest lower MI, it's early August) Aquatic approved (if adjuvants are aquatic-approved) We have applied both of these treatments as either foliar spray or as a "cut stem" application (cutting down stems and filling the stem cavity with herbicide solution), which is a great way to avoid drift and overspray, but is more time-intensive and contains the risk of stem disposal. Questions? Comments? Leave a note!

Just a quick introduction to the Northwest Michigan Invasive Species Network (ISN) for anyone looking for information--feel free to post questions! You can also contact me directly at kgrzesiak@gtcd.org or our Outreach Specialist, Emily Cook, at ecook@gtcd.org. First, check out our website: HabitatMatters.org. It's full of great introductory information, including partners, priority species, and the articles from our eNewsletter. If you want to get involved, sign up for our eNews! This comes out monthly with ways to get involved with ISN and our many partners. If you want to get into the nitty-gritty bits of ISN, send me an email about joining our GoogleGroup. If you're looking to get some resources from ISN, check out our list of resources. We'll work to keep it updated!