Research — Dr. Bert Cregg, Associate Professor

Current Research Projects

Urban tree selection in a changing climate

Research Techncian: Dana Ellison

Backgound and objectives: Trees in urban and community forests are subject to a myriad of stresses that limit their survival and ability to contribute ecosystem services. Climate change will compound these stresses, especially temperature stresses associated with urban heat island effects. Urban and community landscapes in Michigan are esepcially at risk due to heavy losses of ash trees associated with the emerald ash borer outbreak. 

In this project we will identify street tree cultivars that show a high potential to adapt to potential climate change and urban stresses. The project is being carried out in two phases. In Phase 1 we are conducting intensive greenhouse trials to determine the relative ability of street tree cultivars to acclimate their physiological responses to changing temperature regimes. In Phase 2 we are working with a community forestry partner (Greening of Detroit) to compare the ability of cultivars to acclimate under contrasting urban conditions.




J. Frank Schmidt and Sons Nursery

J. Frank Schmidt Family Charitable Foundation

Renewed Earth, Inc.

Nursery Supplies, Inc.



Environmental control of cone production in Fraser fir Christmas tree plantations

Co-PI's Pascal Nzokou, Jill O'Donnell, Beth Bishop

Grad Student: Brent Crain

Background and objectives: Fraser fir is the most valuable Christmas tree species grown my Michigan producers. Currently, however, profitability of Fraser firs is reduced by prolific cone production. Growers must remove trees by hand in order to produce salable trees since the cones reduce the aesthetic value of the trees. In this project we are investigating the effect of environmental factors on cone production in Fraser fir plantations and comparing the effectiveness of cultural treatments in reducing cone production.




Michigan Christmas Tree Association




Nursery establishment and physiology of difficult to transplant ash alternative species

Co-PI’s: Bob Schutzki, Tom Fernandez, Pascal Nzokou

Graduate Student: Dana Ellison

Background and objective: Many tree species that are commonly recommended as replacements for ash trees lost due to the emerald ash borer (EAB) are difficult to establish in nurseries and landscapes. The physiological basis for poor initial growth of these species is not completely understood but may be related to poor initial root growth following transport and handling from liner production nurseries on the west coast. In this project we will examine the effects of pre-plant handling on transplant stress of ash alternative species in nursery production. The long-term goal of the project is to improve the overall availability and success of important ash alternative species in production nurseries and as street and landscape trees.


  • Michigan State University Project GREEEN
  • J. Frank Schmidt Family Charitable Foundation
  • Scotts, Inc.
  • J. Frank Schmidt and Sons Nursery
  • Renewed Earth, Inc.
  • Nursery Supplies, Inc.

Sustainable nutrient and water management for container tree production

Co-PI’s: Tom Fernandez, Pascal Nzokou


Cregg, B., D.Ellison, R.T. fernandez, and P. Nzokou. 2011. MSU Research Update: Water and nutrient management for container tree production. Michigan Landscape 54(5):39-43.

Background and objective: Landscape tree nurseries in Michigan are faced with several challenges. These include adapting to a shift in the industry from traditional field production to container production, optimizing nutrition and water management to maximize growth while reducing costs and potential environmental impacts, and meeting rising consumer demands for sustainably- or organically-produced landscape materials. For the past four years we have conducted research trials on improving nutrient and water management of landscape conifers and shade trees in Pot-in-Pot container production. (Klooster et al., 2010; Taylor et al., 2009). The overall goals of the current phase of our Pot-in-Pot production research are to expand the capabilities of the system and evaluate components of production systems for container-grown conifers and shade trees that will enable growers to market plants as certified Organic or certified Naturally-grown.

The specific objectives of this project are to:

  1. Increase the research capacity of the MSU Pot-in-Pot research nursery by adding an automated drainage measuring system; making it a state-of-art facility for water and nutrient management research on container-grown landscape trees.

  2. Compare the growth and quality of landscape shade trees and conifers grown with conventional fertilizers and organic-approved fertilizers.

  3. Develop whole-crop water and nutrient budgets for shade tree and conifer crops grown with conventional and organic-certified fertilizers.


  • USDA SCRI Block Grant
  • Michigan Department of Agriculture
  • Michigan Nursery and Landscape Association
  • Scotts, Inc.
  • J. Frank Schmidt and Sons Nursery
  • Renewed Earth, Inc.
  • Nursery Supplies, Inc.
  • Peterson’s Riverview Nursery


Dr. Bert  Cregg, Associate Professor

Dr. Bert Cregg
Associate Professor

A214 Plant & Soil Sciences Building
East Lansing MI 48824-1325

Phone: (517) 355-5191 x 1335
Fax: (517) 353-0890