Ray Hammerschmidt, Ph.D.

Ray Hammerschmidt

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Professor Emeritus of Plant Pathology & Faculty Coordinator of MSU Plant and Pest Diagnostics
Department of Plant, Soil and Microbial Sciences



B.S., Purdue University, Biochemistry
M.S. Purdue University, Plant Pathology
Ph.D., University of Kentucky, Plant Pathology

Overview of current program:

Plants are subjected to infection and attack by many different pathogens. However, the evolution of multiple defenses has allowed plants to effectively defend themselves against many of these attacks. Although many potential constitutive and induced defenses have been identified, the specific role and contribution of each to defense have been defined in only a few cases. Current research is involved in elucidating the nature and role of these defenses in several plant-pathogen systems using cytological, chemical, biochemical and molecular techniques. The major goals are to determine which mechanisms of defense are most important in the expression of resistance. Specific projects include the chemistry and role of phytoanticipins in periderm tissues of Prunus spp. as part of passive defense,  the biochemical nature of defense against potato tuber pathogens,  the role of natural and wound-induced periderm and suberin in potato tubers, and the uptake of chemicals by plants from the environment.

Courses taught:

  • PLP 850, Physiological Plant Pathology

Extension and outreach activities:

  • Co-Director, North Central Diagnostic Network
  • Coordinator, MSU Plant and Pest Diagnostics

Recent Publications:

Rhodes G, Chuang Y-H, Hammerschmidt R, Zhang W, Boyd SA, Li H. 2021. Uptake of Cephalexin by lettuce, celery, and radish from water. Chemosphere 263: Article Number: 127916, DOI: 10.1016/j.chemosphere.2020.127916

Smart A, Byrne J, Hammerschmidt R, Snover-Clift KL, Stack JP, Brenes-Arguedad T, Jones JB, Harmon CL. 2021. Evolving plant diagnostics during a pandemic. Plant Heath Progress https://doi.org/10.1094/PHP-08-20-0074-MR

Alzohairy SA, Hammerschmidt R, Hausbeck MK. 2021. Antifungal activity in winter squash fruit peel in relation to age related resistance to Phytophthora capsici.  Physiological and Molecular Plant Pathology 114: https://doi.org/10.1016/j.pmpp.2021.101603

Wahrenburg Z, Benesch E,  Lowe C, Jimenez J, Vulavala VKR, Lü S, Hammerschmidt R, Douches, Yim WC, Santos P, Kosma DK. 2021. Transcriptional regulation of wound suberin deposition in potato cultivars with differential wound healing capacity. The Plant Journal 107:77-79.

Iles LC, Fulladolsa AC, Smart A, Bonkowski J, Creswell T, Harmon CL, Hammerschmidt R, Hirch RR, Rodriguez Salamanca L. 2021. Everything Is Faster: How Do Land-Grant University–Based Plant Diagnostic Laboratories Keep Up with a Rapidly Changing World? Annual Review of Phytopathology 59: 333-349.

Alzohairy SA, Hammerschmidt R, Hausbeck MK. 2020. Changes in Winter Squash Fruit Exocarp Structure Associated with Age-Related Resistance to Phytophthora capsici. Phytopathology  110: 447-455.

Devkota P, Hammerschmidt R. 2020. The infection process of Armillaria mellea and Armillaria solidipes. Physiological and Molecular Plant Pathology 112: Article Number: 101543; DOI: 10.1016/j.pmpp.2020.101543.

 Kaiser NR, Coombs JJ, Felcher KJ, Hammerschmidt R, Zuehlke ML, Buell CR, Douches DS 2020. Genome-wide association analysis of common scab resistance and expression profiling of tubers in response to Thaxtomin A treatment underscore the complexity of common scab resistance in tetraploid potato. American Journal of Potato Research 97: 513-522.

 Devkota P, Iezzoni A, Gasic K, Reighard G, Hammerschmidt R. 2020. Evaluation of the susceptibility of  Prunus rootstock genotypes to Armillaria and Desarmillaria species. European Journal of Plant Pathology 158:177–193

Mambetova S, Rosenzweig N, Hammerschmidt R, Abney M, Jordan B, Culbreath A. 2019. First report of pod wart disease of peanut caused by Streptomyces spp. in the Western Hemisphere. New Disease Reports 40:4.

Chuang Y-H, Liu C-H, Sallach JB, Hammerschmidt R, Zhang W, Boyd SA, and Li H. 2019. Mechanistic study on uptake and transport of pharmaceuticals in lettuce from water. Environment International 131: Article 104976.

Devkota P, Hammerschmdit R. 2019. A rapid and holistic approach to screen susceptibility of Prunus species to Armillaria root rot. Forest Pathology 49:e12547.

Hammerschmidt R. 2018. How glyphosate affects plant disease development:  It's more than enhanced susceptibility. Pest Management Science. 74: 1054-1063.

Chuang Y-H, Liu C-H, Hammerschmidt R, Zhang W, Boyd SA, and Li H. 2018. Metabolic Demethylation and Oxidation of Caffeine during Uptake by Lettuce. Journal of Agricultural and Food Chemistry 2018 66: 7907-7915.

Selected Professional Affiliations, Awards and Honors:

American Chemical Society

American Phytopathological Society

Sigma Xi


Fellow, The American Phytopathological Society (2007)

USDA NIFA Partnership Award for Innovative Program Models (2010)

Cherry Industry Distinguished Service Award, Cherry Marketing Institute (2016)

Distinguished Service Award, NC Division of the American Phytopathological Society (2017)

Outstanding Extension Specialist, Michigan State University Extension (2017)

Distinguished Service to Agriculture Award, Michigan Potato Industry Commission (2021)