Christmas tree farm update June 17, 2026

Bill Lindberg<lindbe35@msu.edu> and Bert Cregg<cregg@msu.edu>, Michigan State University Extension - June 22, 2026

Updates on weather, insect treatment windows and future meetings for Christmas tree production.

map depicting information discussed in text of story for decoration — Photo 1: Growing degree day accumulations across Michigan range from 400 GDD50 in the upper peninsula to about 1,000 GDD50 in the southern lower peninsula.

Weather update

Growing degree day accumulations across Michigan range from 400 GDD50 in the upper peninsula to about 1,000 GDD50 in the southern lower peninsula (Photo 1). These values are about 1 week ahead of normal for the majority of the state (Photo 2).

Photo 2-lindberg.png — Photo 2: Growing degree day accumulations across Michigan range from 400 GDD50 in the upper peninsula to about 1,000 GDD50 in the southern lower peninsula. These values are about one week ahead of normal for the majority of the state.

Insect update

Spongy moth treatment windows are closing for counties in the southern lower peninsula (Photo 3), but treatment windows remain open for many northern counties. If you have not yet applied your spongy moth treatments, remember that treatment windows for all products close at 800 GDD50.

Photo 3- lindberg spongy moth.png — Photo 3: Spongy moth treatment windows are closing for counties in the southern lower peninsula.

News and Notes

We had the opportunity to attend the 17^th IUFRO International Christmas Tree Research and Extension Conference earlier this month in North Carolina. These biennial meetings provide a forum for Christmas tree researchers and extension personnel from North America and Europe to share their latest activities. North Carolina State University hosted this year’s meeting and associated field tours, which provided an opportunity for us to contrast the Christmas tree production in North Carolina (2^nd in the United States in Christmas tree production) and Michigan (3rd-ranked producer). Some key production differences between Michigan and North Carolina included:

Phytophthora root rot (PRR) pressure

Although Michigan growers have experience with various root rots, the disease pressure in North Carolina production seems greater (Photo 4). This could be due to many factors, including past production practices, gradient of hills in field, the severity of the phytophthora species present (P. cinnamomi), weather conditions, amongst other factors. To combat this intense pressure, some growers have begun grafting Fraser trees onto more resistant rootstock (ex. Momi or Canaan fir) (Photo 5). This challenge is also a key research priority in North Carolina State University and many active genetic/molecular research projects are ongoing to find solutions.

Photo 4 - lindberg.jpg — Photo 4: Although Michigan growers have experience with various root rots, the disease pressure in North Carolina production seems greater.

Photo 5- Lindberg.jpg — Photo 5: Some growers have begun grafting Fraser trees onto more resistant rootstock (ex. Momi or Canaan fir)

Weed control goals

Due to steep elevations of Christmas tree fields in North Carolina (Photo 6), the objective of weed control is not to eliminate weeds in row (a common practice in Michigan), but to either stunt weed growth or have small, annual broadleaf weeds that offer less competition for tree growth. Weed control in North Carolina this year has been challenged due to extremely warm and dry conditions to start the 2026 growing season.

Photo 6 lindberg.jpg — Photo 6: Weed control in North Carolina this year has been challenged due to extremely warm and dry conditions to start the 2026 growing season.

Drone use

Drone use in Christmas tree production in North Carolina has “taken off” again due to high hills/slopes in tree production fields. Some growers are utilizing drones for herbicide, insecticide, and fertilizer applications. A novel research trial included impregnating granular herbicide with a fertilizer and making a single application. More research is ongoing looking into the effectiveness of these applications with drone application.

Upcoming Christmas Tree Meetings

The Michigan Christmas Tree Association summer field day (Photo 7) will be July 23 and 24, 2026. MSU Christmas tree team members will provide educational content for the meeting. Membership in MCTA is not a requirement to attend the event. More information, including a detailed agenda can be found at mcta.org.

Photo 7.png — Photo 7: The Michigan Christmas Tree Association summer field day promotion.

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