Fall Herbicide Applications to Control Key Invasive Weeds

Fall is an excellent time to control invasive weeds.  Late summer and fall rains provide land managers with a good opportunity to extend their application season.

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Russian Knapweed

Milestone at 5 or 7 fluid ounces per acre (fl oz/A) is highly effective for controlling Russian knapweed. Unlike other herbicides, applications of Milestone can be made on Russian knapweed through late summer and until after the foliage has died back (leaves are brown and dead) in fall.  Milestone is taken up by Russian knapweed foliage, through the root crown and/or from the soil, and provides long-term control of plants.

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Spotted and Diffuse Knapweed

The application window for treating spotted and diffuse knapweed can be extended depending on the herbicide selected.  Milestone at 5 or 7 fl oz/A applied to spotted knapweed in fall gave excellent control (>95%) of both established plants and seedlings up to 2 years after treatment in Montana. Applications can be made up to late October or early November before soil freezes.

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Canada Thistle

Field research has shown that fall applications are effective with Milestone at labeled rates of 5 to 7 fl oz/A.  Tank mixing with another herbicide is not necessary; Milestone alone will control Canada thistle. University of Nebraska research reports Canada thistle is actually more susceptible to herbicides when applied in the fall following a frost.  Applications can be made in the fall as long as there is live Canada thistle foliage.  Even though Canada thistle leaves will begin to senesce, generally there is still good control up to late October as long as there is some green foliage.

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Biennial Thistles

Fall herbicide treatments may be applied to rosettes over a long period of time in fall. Milestone® at 3 to 5 fl oz/A provides excellent control of biennial thistle (e.g. musk, bull, and plumeless thistle).  An additional advantage is that fall treatments reduce the potential of injury to non-target, desirable broadleaf plants from spray drift since many are dormant.

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Tamarisk (saltcedar) and Russian Olive

Fall is an excellent time to maintain grass understory and control re-sprouting on tamarisk and Russian olive with a tank-mix of Milestone herbicide with Garlon® 4 Ultra or Remedy® Ultra specialty herbicides.  You should wait least 6 months after cutting to allow time for the plants to regrow and develop adequate leaf area for more herbicide uptake with a foliar application. Apply Milestone at 7 fluid ounces per acre plus Garlon® 4 Ultra or Remedy® Ultra at 3 quarts per acre (qt/A) with a non-ionic surfactant at 0.25% v/v or 1 qt/A of methylated seed oil (MSO). This treatment allows grasses to flourish and will also control broadleaf weeds such as Canada thistle, musk thistle, Russian knapweed, and many others that may invade the area after cutting. Tamarisk and Russian olive control may not be complete with just a single application so the site should be monitored in subsequent years and re-sprouts treated for complete control.

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Other Species

 

Fall application of Milestone at 5 to 7 fl oz/A also provides excellent control of absinth wormwood, oxeye daisy, and several other invasive plants as indicated on the label. 


Published August 2010; Updated September 2018


 

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Milestone® specialty herbicide is not registered for sale or use in all states. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state. When treating areas in and around roadside or utility rights-of-way that are or will be grazed, hayed, or planted to forage, important label precautions apply regarding harvesting hay from treated sites, using manure from animals grazing on treated areas or rotating the treated area to sensitive crops. See the product label for details.

State restrictions on the sale and use of Milestone apply. Consult the label before purchase, or use for full details. Always read and follow label directions.