Area of expertise: physiology and management of trees in landscapes and nursery production
Dr. Bert Cregg conducts research and extension programs on tree physiology and management of nursery, landscape, and Christmas tree systems.
Key research and extension program areas include:
- Slope restoration on urban freeways
- Culture and genetics of Christmas tree production
- Water and nutrient management of shade trees and conifers in Pot-in-Pot production
- Promotion of increased tree species diversity in urban and community forests
Current Research Projects
Landscape plant selection and management for slope restoration on urban freeways
Background and objectives: In this project we are investigating strategies to improve establishment of landscape plants on urban freeway roadsides. In the summer and fall of 2018, we established a series of replicated plots along I-696 north of Detroit in collaboration with the Michigan Department of Transportation (MDOT) to evaluate landscape plants (shrubs, herbaceous perennials, and grasses) and site preparation practices for slope restoration along urban freeways. Results from this research will inform decisions on site preparation practices and plant selection for similar sites in Michigan and the Midwest. Expanding the range of plant selections for roadside plantings beyond turfgrasses will provide new markets and opportunities for Michigan nurseries.
- Robert Schutzki
- Maddy Dubelko (graduate student)
- Michigan Department of Transportation
- MSU Project GREEEN
- Michigan Department of Agriculture and Rural Development Horticulture Fund Greening of Detroit
Culture and genetics of Christmas tree production
Research and extension efforts at MSU are addressing several key and emerging issues for Michigan Christmas tree producers. Current research projects include;
- Understanding environmental control of coning in Fraser fir
- Use of plant growth regulators to control coning and shoot growth of conifers
- Establishment of a Fraser fir seed orchard at the Horticulture Teaching and Research Center
- Establishment of large-scale test plantations of Turkish and Trojan fir as part of the Collaborative Fir Germplasm Evaluation (CoFirGE) project; a multi-institution program with North Carolina State University, Oregon State University, Washington State University, and Pennsylvania State.
- MSU Project GREEEN
- Christmas Tree Promotion Board Research Fund
- Michigan Christmas Tree Association
Improving transplant success of container-grown landscape trees
In this project we are examining long-term responses of trees to nursery culture, planting and maintenance in order to better understand the role of each step in tree survival and growth. We are comparing innovative practices, such as root-shaving or bare-rooting container-grown trees at planting and application of plant growth regulators in the nursery, on long-term performance of trees in landscapes. The results of this research will provide nursery managers, landscape contractors, and urban foresters with additional tools to improve the long-term success of landscape and street tree plantings.
Goals / Objectives
- Evaluate the impact of nursery cultural techniques on physiology and morphology of nursery stock and subsequent transplant success
- Evaluate the impact of transplant techniques on transplant success of container grown trees
- Determine the impact of mulching after planting on long-term success of container-grown landscape trees
- Riley Rouse (Research Technician)
- Michigan State University Project GREEEN
- J. Frank Schmidt Family Charitable Foundation
- ICL Specialty fertilzers
- Rainbow Scientific
- J. Frank Schmidt and Sons Nursery
- Renewed Earth, Inc.
- Nursery Supplies, Inc.
Physiology of nursery crops irrigated with recycled run-off
Co PI’s: Tom Fernandez (MSU lead), Bridget Behe
Graduate Student: Shital Poudyal
- Access to high quality water for nursery irrigation is increasingly limited. Growers need to develop alternative sources of water (e.g. recycled water). Stakeholder reluctance to use recycled water is motivated by the presence of pathogens and agrichemical contaminants, and the lack of readily available information about treatment technologies in terms of economic viability and efficacy.
- As part of a Multi-institution USDA SCRI project (Clean WateR3 - Reduce, Remediate, Recycle) we are investigating the potential impacts of irrigating nursery crops with remediated and recycled run-off water. Understanding the impacts of recycled water on crop health and function is critical to grower acceptance of these emerging technologies.
- USDA NIFA SCRI
- MSU Project GREEEN
- Michigan Department of Agriculture and Rural Development
- Michigan Nursery and Landscape Association
- Renewed Earth, Inc.
- Nursery Supplies, Inc.
- Rouse, R. P., & Cregg, B. 2021. Species and season affect response of container-grown shade trees to pre-plant root modifications. Urban Forestry & Urban Greening, 63, 127184.
- Poudyal, S., Owen Jr, J. S., Sharkey, T. D., Fernandez, R. T., & Cregg, B. 2021. Phosphorus requirement for biomass accumulation is higher compared to photosynthetic biochemistry for three ornamental shrubs. Scientia Horticulturae, 275, 109719.
- Saha, D., Cregg, B. M., & Sidhu, M. K. 2020. A review of non-chemical weed control practices in Christmas tree production. Forests, 11(5), 554.
- Poudyal, S., Owen, J. S., Fernandez, R. T., & Cregg, B. 2020. Sensitivity of Hydrangea paniculata plants to residual herbicides in recycled irrigation varies with plant growth stage. Water, 12(5), 1402.
- Cregg, B., & Ellison-Smith, D. 2020. Application of Paclobutrazol to Mitigate Environmental Stress of Urban Street Trees. Forests, 11(3), 355.
- Kwak, M., Hong, J. K., Lee, E. S., Lee, B. Y., Suh, M. H., & Cregg, B. (2020). Evaluation of Genetic Diversity in Korean Fir Cultivars Based on Microsatellite and Cytoplasmic Markers. Journal of the American Society for Horticultural Science, 145(1):45-52.
- Poudyal, S., Fernandez, R. T., Owen, J., & Cregg, B. (2019). Dose-Dependent Phytotoxicity of Pesticides in Simulated Nursery Runoff on Landscape Nursery Plants. Water, 11(11), 2354.
- Vandegrift, D. A., Rowe, D. B., Cregg, B. M., & Liang, D. (2019). Effect of substrate depth on plant community development on a Michigan green roof. Ecological Engineering, 138, 264-273.
- Cregg, B., & Ellison, D. (2018). Growth and establishment of container-grown London planetrees in response to mulch, root-ball treatment and fertilization. Urban Forestry & Urban Greening, 35, 139-147.
- Cregg, B., Ellison, D., & O’Donnell, J. (2018). Post-Emergent Control of Nuisance Cones in Fraser Fir Christmas Tree Plantations. Forests, 9(5), 233.
- Crain, B. A., & Cregg, B. M. (2017). Using irrigation and mulch to control cone production in Fraser fir (Abies fraseri). Scandinavian Journal of Forest Research, 32(5), 384-390.
- Crain, B. A., Nzokou, P., O’Donnell, J., Bishop, B., & Cregg, B. M. (2018). Robust Model Predicts Shoot Phenology of Fraser Fir under Extreme Conditions. Forests, 9(4), 193.
- Ellison, D.S., R. Schutzki, P. Nzokou, B. Cregg. 2016. Root growth potential, water relations and carbohydrate status of ash alternative species following pre-plant storage. Urban Forestry and Urban Greening18: 59-64.
- Tanis, S. R., McCullough, D. G., & Cregg, B. M. 2015. Effects of paclobutrazol and fertilizer on the physiology, growth and biomass allocation of three Fraxinus species. Urban Forestry & Urban Greening, 14: 590-598.
- Whittinghill, L. J., Rowe, D. B., Schutzki, R., & Cregg, B. M. 2014. Quantifying carbon sequestration of various green roof and ornamental landscape systems. Landscape and Urban Planning, 123, 41-48.
- AÄ‡imoviÄ‡, S. G., VanWoerkom, A. H., Reeb, P. D., Vandervoort, C., Garavaglia, T., Cregg, B. M., & Wise, J. C. 2014. Spatial and temporal distribution of trunkâ€injected imidacloprid in apple tree canopies. Pest management science, 70(11), 1751-1760.
- Taylor, J.T., R.T. Fernandez, P. Nzokou, and B.M. Cregg. 2013. Carbon isotope discrimination, gas exchange, and growth of container-grown conifers under cyclic irrigation. HortScience 48:848-854.
- Klooster, W.S., B.M. Cregg, R.T. Fernandez, and P. Nzokou. 2012. Growth and physiology of deciduous shade trees in response to controlled release fertilizer. Sciencia Horticulturae 135:71-79.
- Tanis, S.R., B.M. Cregg, D. Mota-Sanchez, D.G. McCullough, and T.M. Poland. 2012. Spatial and temporal distribution of trunk-injected 14C-imidacloprid in Fraxinus trees. Pest Manag Sci. 68: 529-536.
- Kim, S. and B.M. Cregg. 2012. Emerging methods for diagnostics and mitigation of crop environmental stress in a changing climate. HortScience 46:684-686.
- Wilson, A.R., P. Nzokou, and B.M.Cregg 2010. Ground covers in Fraser fir produciton: Effects on soil fertility, tree morphology and folair nutrient status. European J. Hort. Sci. 75(6) S. 269-277.
- Klooster, W.S., B.M. Cregg, R.T. Fernandez, and P. Nzokou. 2010. Growth and photosynthetic response of Pot-in-pot-grown conifers to substrate and controlled-release fertilizer. HortScience 45:36-42.
- Nzokou, P. and B.M. Cregg. 2010. Growth, biomass, and nitrogen use efficiency of containerized Fraser fir (Abies fraseri) as related to irrigation and nitrogen fertilization. HortScience 45:946-951.
- Nzokou, P. and B.M. Cregg. 2010. Morphology and foliar chemistry of containerized Abies fraseri seedlings as affected by water availability and nutrition. Ann. For. Sci. 67:602-611.
- Cregg, B.M. P. Nzokou, and R. Goldy. 2009. Growth and physiology of newly planted fraser fir (Abies fraseri) and Colorado blue spruce (Picea pungens) Christmas trees in response to mulch and irrigation. HortScience 44:660-665.
- Cregg, B.M. and R. Schutzki. 2009. Weed control and organic mulches affect physiology and growth of landscape shrubs. HortScience 44:1419-1424.
- Gooch, N.J., P. Nzokou, and B.M. Cregg. 2009. Effect of indoor exposure on the cold hardiness and physiology of containerized Christmas trees. HortTechnology 19:72-77.
- Jones, G.E. and B.M. Cregg. 2006. Screening exotic firs for the Midwestern United States: Interspecific variation in adaptive traits. HortScience 41:242-328.
- Jones, G.E. and B.M. Cregg. 2006. Budbreak and winter injury in exotic firs. HortScience 41:143-148.
- Rothstein, D.E., and B.M. Cregg. 2005. Effects of nitrogen form on nutrient uptake and physiology of Fraser fir (Abies fraseri) For. Ecol. and Mgmt.219 69-80.
- Zhang, J. and B.M. Cregg. 2005. Growth and physiological responses to varied environments among populations of Pinus ponderosa. For. Ecol and Mgmt. 219 1-12.
- Duck, M.W., B.M. Cregg, R.T. Fernandez, and R.D. Heins 2004. Height control of Picea spp. and Chamaecyparis lawsoniana with Uniconazole and 6-Benzyladenine Journal of Environmental Horticulture 22:165-169.
- Duck, M.W., B.M. Cregg, R.T. Fernandez, and R.D. Heins 2004. Controlling growth of conifers with six common plant growth retardants. HortTechnology 14(4) 1-5.
- Cregg, B.M., M.W. Duck, C.M. Rios, D.B. Rowe, and M.R. Koelling 2004. Chlorophyll fluorescence and needle chlorophyll concentration of fir (Abies spp.) seedlings in response to pH. HortScience 39:1121-1125.
- Cregg, B.M. 2004. Selecting trees for improving drought tolerance: theoretical and practical consideration.Acta Horticulturae 630:147-156.
Selected Extension Publications
- Cregg, B. 2016. Are natives the answer? Powerpoint presentation.
- Cregg, B. 2015. Trees and Turf: Can’t we all just get along? The Michigan Landscape 58(1):32-35.
- Cregg, B. 2014. Right tree-right place: Flooding and poor drainage. The Michigan Landscape 57(4):39-43.
- Cregg, B. 2014. Right tree-Right place: Alkaline soils. The Michigan Landscape 57(6):43-47.
- Cregg, B. and D. Ellison. 2013. Urban tree selection in a changing climate. The Michigan Landscape 56(6): 28-30.
- Stelzer, H. and B. Cregg. 2013. FAQ’s for helping your tree survive during a drought. Extension Disaster Education Network (EDEN) 6 pp.
- Fulbright et al. 2012. Phompsis Spruce Decline. The Michigan Landscape. 55(5):30-32.
- Cregg, B. 2012. A homeowner’s guide to nutrition and fertilziation of landscape trees and shrubs.
- Cregg, B. 2012. Alternative conifers for Michigan landscapes.
- Cregg, B. and K. Frank. 2011. A Homeowner’s guide to Imprelis herbicide injury in landscape trees.
- Cregg, B. 2011. Going native with Michigan trees. The Michigan Landscape 54(3): 31-34.
- Cregg, B. 2011. Beyond blue spruce: Uncommon conifers for Michigan Landscapes. Meadowbrook Garden Club. Rochester, MI, March 24, 2011.
- Cregg, B. 2011. Effect of organic mulches on soil properties, physiology, and growth of landscape shrubs. SE Oakland County Water Authority, Bingham farms, MI, March 8, 2011.
- Cregg, B. 2011. Tree selection for urban communities: natives, exotics, and common sense. Global Re-Leaf of Michigan, Midland, MI, Feb. 23, 2011.
Dealing with storm-damaged trees
Published on August 25, 2023
Christmas Tree Planting Guide (E3481)
Published on August 8, 2023
Drought conditions begin to impact Michigan landscapes
Published on June 21, 2023
MSU Extension bulletin highlights alternatives to blue spruce
Published on May 11, 2023
The cone wars: How do we stop them?
Published on May 8, 2023
Alternatives to Blue Spruce: Top Conifers for Michigan Landscapes
Published on April 30, 2023
The top 10 do’s and don’ts of Christmas tree planting
Published on March 28, 2023
What can I plant to replace my storm-damaged tree?
Published on March 1, 2023
Addressing ice storm damage to trees
Published on February 27, 2023