MELeaf: A Newsletter From the Horticulture Program, December 5, 2023

Maine Department of Agriculture, Conservation and Forestry sent this bulletin at 12/05/2023 03:30 PM EST

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Horticulture Program

MELeaf: A Newsletter From the Horticulture Program, December 5, 2023

In this issue:

A Pair of Box Tree Moth Meetings: What We Learned and What You Should Know

The invasive insect box tree moth (Cydalima perspectalis) has now become established in four states after its initial North American detection five years ago in Canada. This fall, DACF staff have participated in the following trainings to learn more, in an effort to prevent it from becoming established in Maine. 

In Ohio: Karen Coluzzi, Pest Survey Coordinator, learned how state, federal, and Canadian agencies, as well as industry, are working together to find solutions to managing this new challenging pest. Federal quarantines are mirroring state quarantines in parts of New York, Michigan, and Ohio. Massachusetts will soon have a whole state quarantine. State and federal officials are being trained to inspect boxwood plants for cryptic life stages, especially the overwintering stage where young larvae “glue” together a few leaves to hibernate within (see photo below). Much research is being conducted on effective treatment options, including traditional and bio-pesticides, as well as biocontrols and mating disruption techniques. USDA and affected states (NY, MI, OH, and MA) have developed outreach materials.  

In New York: Carole Neil, Horticulture Inspector, attended an interstate inspection training hosted by the Horticultural Inspection Society, Eastern Chapter. This group of inspectors as well as state and federal cooperators visited boxwood production nurseries and learned how New York is handling certification of boxwood for shipment.   

In quarantined areas: 

  • No boxwood is allowed to leave areas quarantined for box tree moth, 
  • Boxwood plants being sold or shipped within the quarantine must undergo a rigorous inspection process.  

Non-quarantined area nurseries are also being carefully inspected to: 

  • Monitor the boundaries of the infestation and hence the quarantine,  
  • Ensure shipments of boxwood to other areas in NY and other states are pest free.  

This insect completes multiple overlapping life cycles in one year, all of which occur on above ground portions of boxwood plants. Therefore, during the growing season multiple visual inspections are required to look for all life stages of this small and well camouflaged insect. Many inspectors found the process of handling interior areas of the foliage to be concerning, due to previous warnings that this method of inspecting could spread the fungal disease boxwood blight, if present.

To learn more, check back to the July MELeaf. 

To request outreach materials and for further info, email horticulture@maine.gov 

Damage to boxwoods from boxtree moth.

Defoliation of boxwoods due to box tree moth

Overwintering boxtree moth

Box tree moth overwinters as small caterpillars inside hibernacula -protective structures that are made from several boxwood leaves stuck together.

Don't Get Caught by Surprise! Expanded Invasive Plant Rule Goes Fully into Effect January 1, 2024

The invasive plant rule review that was completed in 2022 included a phase in period and the full rule goes into effect starting January 1, 2024. As the rule goes into effect, what do you need to know? 

30 Species Added to the Do Not Sell List 

Starting January 1, 2024 an additional 30 species join the existing 33 species on the Invasive Plant Do Not Sell List. Any remaining inventory of these plants cannot be offered for sale and must be removed from sales areas. The ban includes all hybrids, cultivars or varieties of the species on the list as well as all viable parts of the species including rootstocks. 

Rosa rugosa Signage or Label Required 

The 2022 rule review added Rosa rugosa to a new category of Invasive Species of Special Concern. Species listed in this category may still be sold, but the rule requires they be sold with specific signage or labeling indicating the plant could be invasive under certain conditions.  

The Horticulture Program has a supply of signs printed on weather resistant material that meet the requirements found in the rule. You can request these free signs by emailing horticulture@maine.gov. Alternatively, anyone attending the Grow Maine Green Expo or the Maine Agricultural Trades Show in January can visit the Plant Health Programs (trades show) or Horticulture Program (GMG) booths to pick up signs in person. 

For businesses that prefer to create or print their own signs or labels, examples and specific requirements can be found on the Invasive Plant webpage.   

An example of a sign that must be displayed with Rosa rugosa plants that are for sale.

An example of a sign that must be displayed with Rosa rugosa plants that are offered for sale. Request copies of this sign, printed on weather resistant material, by emailing horticulture@maine.gov

Outreach Materials Available 

The Horticulture Program has assembled invasive plant outreach materials that can help educate you, your staff and your customers. Request any of these materials by emailing horticulture@maine.gov or come visit our booth at the Grow Maine Green Expo or Maine Agricultural Trades Show: 

  • Plant This, Not That! Bookmarks – Now with designs featuring 8 of the plants on Do Not Sell List.
  • Do Not Sell List Factsheet – Full page, 2-sided factsheet that includes invasive plant quick facts and the full list of plants on the Do Not Sell List. 
  • Hitchhiker Postcards – In two different designs, one featuring mile-a-minute vine and the other invasive stiltgrass. Both plants are known to move with nursery stock and are of limited distribution in Maine.
  • Invasive Plant Guide for Maine Horticultural Businesses – A comprehensive manual that covers all the information Maine plant sellers need to comply with the invasive plant rule including: 
    • Copies of the invasive plant rule, 
    • The full list of plants on the Do Not Sell List, including any synonyms and common cultivars,
    • List of alternative plant suggestions for invasive plants, 
    • An identification guide for invasive plants,
    • And more! 
  • Coming Soon! Customer Focused Factsheets for In-Demand Plants on the Do Not Sell List –This factsheet series will help you educate your customers about why you can’t sell certain in-demand plants (like ‘Crimson King’ Norway maple and burning bush). The factsheet will include an explanation of why the plant is included on the Do Not Sell List and suggestions for plants to choose instead. 
Invasive Plant Outreach Materials

Some of the invasive plant outreach materials that are available for educating your staff and customers. Email horticulture@maine.gov to request copies of outreach materials.

It's License Renewal Time!

License renewal applications were mailed just before Thanksgiving. Please review and return the application promptly. Submitting your application early will ensure that you receive your license before selling plants in 2024. 

As a reminder, all businesses or individuals in Maine selling plants must have a License to Sell Nursery Stock. Nursery stock is defined as: 

  • Woody plants, including ornamental and fruiting trees, shrubs, vines and all viable parts of these plants; 
  • Herbaceous plants, including florist stock plants, annuals, perennials, vegetable seedlings, herbs, potted plants and all viable parts of these plants;  
  • Any other plant or plant part designated by the commissioner. 

Businesses that sell only cut flowers, cut Christmas trees or seeds do not need to obtain a License to Sell Nursery Stock.   

Questions? horticulture@maine.gov  

Winter Learning Opportunities

In-Person 

  • January 9-11, 2024: Maine Agricultural Trades Show, hosted by the Maine Department of Agriculture and Forestry (DACF) at the Augusta Civic Center 
  • January 24, 2024: Grow Maine Green Expo, hosted by the Maine Landscape and Nursery Association (MELNA) at the Augusta Civic Center 
  • End of February: Greenhouse Best Practices Workshop hosted by DACF Horticulture and IPM Programs at Longfellow’s Greenhouses, Manchester, Maine. More information coming soon! 

Virtual 

On Demand