Using irrigation and mulch to control cone production in Fraser fir (Abies fraseri)

ABSTRACT

Fraser fir (Abies fraseri) is economically important as a Christmas tree in the United States, but trees often produce cones at a young age when grown in plantations in the Midwest. Early cone production is undesirable and decreases the economic value of the tree. High temperatures and drought are associated with increased reproductive output in conifers. Therefore, we investigated the effects of irrigation and mulch on cone production in two Fraser fir plantations in Michigan. At one site, we applied mulch to one tree in each row, with paired controls. In 2013, irrigation increased soil moisture by 47% under drought conditions, compared to non-irrigated control plots. However, irrigation had no effect on cone production in any year. Mulch reduced average maximum daily soil temperatures 7.4°C in 2013 and 4.8°C in 2014. Mulch reduced cone production in 2014 by 51%, but had no effect the following year, after a cooler summer. Our findings suggest that soil temperature, rather than soil moisture, regulates cone formation in Fraser fir, but treatments that reduce soil temperatures may only be effective in warmer locations or years.

KEYWORDS:

• Heat
• drought
• soil temperature

Acknowledgements

We are grateful to Getty Tree Farms and Wahmhoff Farms Nursery for allowing us to conduct research on trees in their plantations.

Disclosure statement

The authors have no financial interest or benefit arising from direct application of this research.

ORCiD

Brent A. Crain http://orcid.org/0000-0002-7242-1045

Additional information

Funding

We gratefully acknowledge funding from the Michigan Christmas Tree Association, and Michigan’s plant agriculture initiative at Michigan State University (Project GREEEN). This work was supported by the USDA National Institute of Food and Agriculture, Hatch project MICL01978.