Implementing Multiple Strategies to Battle Japanese Beetle

By Laura Pottorff, CGG,  Nursery & Plant Pest Quarantine Program Manager, Colorado Department of Agriculture

Quarantine pests and laws associated with their movement turn out to be one of the most challenging issues for nurseries to address. Unfortunately, when a quarantine pest is forgotten, or not well known, it becomes even more of a risk. The Colorado Department of Agriculture (CDA) pledges to be more diligent in our role to protect the nursery and greenhouse industry from invasive pests like Japanese beetle. In turn, you must also do your part. Choose your source of plant material wisely.

Japanese beetle is spreading throughout Colorado’s Front Range from Pueblo to Fort Collins. However, the pest is not equally abundant in all areas of the urban corridor, neither is it present on the Western Slope and on the eastern plains of Colorado. Nurseries, greenhouses, sod farms, and private property owners who don’t have this pest, both within Colorado and outside our state, want to keep it that way. Colorado-grown nursery and greenhouse exports must still meet quarantine standards for any state where the product is sent.

Our Commitment to Preventing Beetle Spread:

  • Internal quarantine – CDA, with your support, added an internal quarantine of 11 Front Range counties in 2017. A quarantine on nursery stock imported from infested states helps slow the progression of the insect and prevent new Colorado introductions. Nursery stock may only enter Colorado if treated with certain insecticides or certified to be Japanese beetle free. Expansion to include the Colorado counties of Pueblo, El Paso, Douglas, Arapahoe, Jefferson, Denver, Boulder, Broomfield, Adams, Weld, and Larimer helps prevent spread of the pest from known infested areas on the Front Range to locations in eastern Colorado and the Western Slope.
  • Focus on nursery stock records and quarantine enforcement – Records inspections are now treated separately from traditional nursery stock inspections. With a continued influx of plants from areas not previously sourced, we continue to find stock from infested states without proper inspection and JB certification.
  • Law changes – to modernize nursery rules, regulations and strengthen our states’ commitment to managing invasive pests, the current legislative session is considering changes to allow:
  • Inspection of all Colorado nurseries based on pest risk, not on export.
  • Clarification of the definition of sell, broker and distribution of nursery stock. All businesses who are responsible for brokering or distributing nursery stock must also register and follow quarantine rules.
  • Limitation of the size of nursery stock exemptions. Beginning April 15, all nursery stock in containers of one gallon and larger must be certified JB free to enter Colorado or move from the internal quarantine area to protected parts of our state.
  • Biocontrol research – Colorado is viewed by other states to be the leading edge of western Japanese beetle infestation. CDA is partnering with CSU and other western states to do biological control research on the Front Range.

Your Responsibility in Preventing Beetle Spread:

  • Always purchase nursery plants from Japanese beetle-free sources. Don’t be complacent – All nursery stock from the eastern and midwestern U.S. and the 11 Colorado county quarantine area must include certification documents that accompany the stock. These documents describe how that stock meets Colorado’s quarantine. Check with the nursery before you order to make sure they meet quarantine. Remember that soil also carries the pest—fill dirt and soil from infested areas is even more risky than nursery stock!
  • Know where Japanese beetle is – Check CDA’s website for updated maps and information:
  • Educate your clientele – Explain how your nursery is managing this pest, and by doing so, your nursery is certified to be adequately mitigating the risk of Japanese beetle spread.

Check CDA’s website for updated maps and information: