Bert Cregg

Associate Professor

Bert Cregg


1066 Bogue St, Room A214
East Lansing, MI 48824

Phone: 517-353-0335

Area of Expertise: Physiology and management of trees in landscapes and nursery production

Quick links: Education   Professional Experience   Publications   Research


Ph.D. Forest Resources, University of Georgia, 1990.
MPA. Public Administration, University of Nebraska, 1995.
M.S. Forest Science, Oklahoma State University, 1986.
B.S. Forest Management, Washington State University, 1983.
A.S. Forestry, Centralia College, 1980.

Professional Experience

Associate Professor (2003-present) Assistant Professor (1999-2003) Department of Horticulture and Department of Forestry, Michigan State University

Tree Physiology Project Leader (1996-1999) Forest Resources Group, International Paper, Savannah, GA

Research Plant Physiologist (1990-1996) USDA Forest Service, Rocky Mountain Research Station, National Agroforestry Center, Lincoln, NE


Research: 50%
Extension: 50%


Dr. Bert Cregg conducts research and extension programs on tree physiology and management of nursery, landscape, and Christmas tree systems.

Dr. Cregg’s key research and extension program areas include:

  • Urban tree selection in a changing climate
  • Environmental control of cone production in Fraser fir Christmas tree production
  • Water and nutrient management of shade trees and conifers in Pot-in-Pot production
  • Promotion of increased tree species diveristy in urban and community forests
  • Ornamental conifers

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.

  • MSU Project GREEEN
  • 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.

  • MSU Project GREEEN
  • 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

Research Publications

Selected Publications

Proceedings publications

  • Cregg, B.M., P. Nzokou, and R. Goldy. 2008. Growth and physiology of newly planted Fraser fir (Abies fraseri) and Colorado blue spruce (Picea pungens) in response to mulch. IN: Thomsen, I.M., Rasmussen, H.N. & Sørensen, J.M. (Eds.): Proceedings of the 8th International Christmas Tree Research and Extension Conference. Forest & Landscape Working Papers No. 26-2008, Forest & Landscape Denmark, Hørsholm, p.61-64.
  • Cregg, B.M. D. Mota-Sanchez, D.G. McCullough, T. Poland, and R.M. Hollingowrth. 2006. Distribution of 14C Imidacloprid in Fraxinus spp. and effects of imidacloprid on EAB adults. IN: Emerald Ash Borer: Research and Technology Development Meeting USDA Forest Service and USDA APHIS Forest Service Forest Health Enterprise Team Report FHTET 2005-19. pp.24-25.
  • Cregg, B.M. and Grant Jones. 2005. Interspecific variation in adaptive traits of true firs (Abies spp). Proc. Southern Nursery Association Aug. 8-10 Atlanta, GA.
  • Coleman, M.D., Coyle, D.R., Blake, J., Britton, K., Campbell, R.G., Cox, J., Cregg, B.M., Daniels, D., Jacobson, M., Johnsen, K., McDonald, T., McLeod, K., Nelson, E., Robison, D., Sanchez, F., Standturf, J., Stokes, B., Trettin, C., Tuskan, J. Wright, L., and Wullschleger, S. 2004. Production of short-rotation woody crops grown with a range of nutrient and water availability: establishment report and first-year Reponses. USDA Forest Service Southern Research Station General Technical Report SRS-72. 21 p.

Extension Publications — Dr. Bert Cregg, Associate Professor

Recent Extension Presentations and Publications

Extension Bulletins

  • Schutzki, R. and B. Cregg. 2007 Abiotic plant disorders. A diagnostic guide to problem-solving. MSU Extension Bulletin E-2996. 16 pp.
  • Cregg, B. and R. Schutzki. 2006. Recommended ash alternatives for Michigan’s Lower Peninusula. MSU Extension Bulletin E-2925. 12 pp.

Pot-in-Pot production

  • Cregg, B.M., W. Klooster, R.T. Fernandez, and P. Nzokou. 2009. Container production for living Christmas trees. Great Lakes Christmas Tree Journal 4(1): 37-41.
  • Cregg, B.M. 2006. Pot-in-Pot Research at MSU: A growing partnership. The Michigan Landscape 49:49-52.

 “Conifer Corner” articles from the Michigan Landscape magazine

Conifers by size class:
Conifers by form class
Conifers by species
Conifer species profiles from the Great Lakes Christmas Tree Journal
Other topics



Weather/Climate links

Imprelis links


Program Areas — Dr. Bert Cregg, Associate Professor

Ornamental and Landscape Ecology

  • Water and nutrient management of shade trees and conifers in Pot-in-Pot production
  • Production of ash replacement species
  • Promotion of increased tree species diveristy in urban and community forests
  • Movement and distribution of trunk-injected systemic insecticides for EAB
  • Ornamental conifers