Approved Regulatory Treatments for Spongy Moth

Research shows that spruce, fir, and Douglas-fir support all spongy moth (gypsy moth/Lymantria dispar) life stages. A visual inspection alone is not adequate to certify that cut Christmas trees are free of this pest when spongy moth is in the area.

Acceptable pesticides for preventative treatment

The grower can use any pesticide that is labeled for the site for preventative treatments. However, if spongy moth (gypsy moth/Lymantria dispar) is present on the premises or surrounding area, an approved regulatory treatment must be applied (see Table 1). If one or more of the following sites are listed on the label, then the pesticide is acceptable for use on Christmas trees:

• Planted fields
• Forest trees
• Conifers
• Forest tree plantings
• Tree species
• Forest tree nurseries
• Evergreens
• Non-ornamental trees

Label claims for product use on "woody ornamentals, ornamentals or nursery stock" are not acceptable for use on Christmas trees.

Required documentation

The grower must maintain a record of each pesticide application made and must make such records available to MDARD on their application for inspection or upon request by MDARD.

Questions regarding pesticide applications can be sent to:

Tips for Successful Spongy Moth (gypsy moth/Lymantria dispar) Control

1. Dimilin- Growers are advised to direct sprays at early instars to achieve best control.
2. Contact Sprays - Growers selecting contact sprays must consider the development of the larvae at the time of application as well as the residual value of the pesticide. Late instar larvae crawling into trees to pupate might not be affected by contact insecticides applied early in the season; a risk that might be reduced if a second contact insecticide was applied.
3. Coverage - Thorough coverage and water volumes are essential for successful applications. Growers should consult with their commercial applicators, sales representatives, or MSU Extension for the best information on successful spray coverage.

MDARD to assure proper control of spongy moth (gypsy moth/Lymantria dispar) in what the USDA refers to as "hazardous sites." These are defined as sites where this pest is present on the premises and/or in the surrounding area. Christmas tree fields and nurseries where egg masses have been found the previous year are considered hazardous sites. The following insecticide active ingredients have been approved as acceptable regulatory treatments for use on Christmas trees. Use of an insecticide not on the following list for regulatory treatment of a hazardous site will result in denial of certification.

All applications must be applied at the maximum labeled rate. The product must be a registered pesticide in Michigan. MDARD’s Pesticide and Plant Pest Management Division publishes a list of registered pesticides in Michigan. See the link for “Pesticides Registered in Michigan” atMichigan.gov/PestReg

Contact MSU Extension for assistance in selecting a product and determining adequate timing of applications.