April Weed of the Month: Annual Treatment Cycle for Invasive Plant Species

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April 1, 2024

April Weed of the Month: Annual Treatment Cycle for Invasive Plant Species

Invasive plant management occurs throughout the year and depends on the growth habit and lifecycle of the species.

Maya Sarkar, Minnesota Department of Agriculture

Its been a warm winter in Minnesota and our plant life is celebrating spring early this year. While it's still fairly quiet in the plant world compared to our main summer growing season, it’s a great time to get started on controlling some invasive plant species.

Invasive plant management occurs throughout the year and depends on the growth, habit, and lifecycle of the species. Plant types include woody, herbaceous annual, herbaceous biennial, or herbaceous perennial plants.

  • Spring is a great time to pull garlic mustard before it seeds. It’s also a good time to use prescribed fire to burn invasive plants before many native prairie plants emerge.
  • Summer months are ideal for controlling plants that are accessible and actively growing but haven’t produced seed yet, such as spotted knapweed.
  • Fall is a good time to spray herbaceous biennials and perennials because they will move herbicide along with carbohydrates into their roots as they store energy for spring emergence.
  • In the winter, while herbaceous plants are dormant it can be advantageous to cut and treat woody vines, such as roundleaf bittersweet.

While accessibility is one planning factor for treatment, there are numerous other considerations, including:

  • Knowing which treatment method will be most effective depending on the lifecycle stage of the plant.
  • Spraying outside of the plant’s bloom window to avoid spraying pollinators. Another way to avoid pollinators is to spray early in the morning before pollinators are active.
  • Having the correct materials, equipment, and sufficient time to complete a treatment thoroughly.

The following is a helpful general treatment guideline for the seasons when it comes to general characteristics of an invasive species, including growth, habit, and lifecycle.

Chart with four seasons with best weed management techniques in each

Each season has unique weed management techniques that can be used to control noxious weeds. 

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Additional online resources:


MEDIA: For more information on Weed of the Month, contact Brittany Raveill, MDA Communications, at brittany.raveill@state.mn.us or 651-201-6131