My research program investigates the ecology of fungus and fungus-like plant pathogens for enhanced and integrated disease management.  Specifically, we investigate Phytophthora species pathogenic on potato and vegetable crops in field and storage.  My program conducts research on P. infestans, P. capsici, and P. erythroseptica to determine pathogen genotypes/races/clonal lineages, mating types, host range, virulence, survivability, and resistance to commonly utilized fungicides.  Improved understanding of pathogen characters has promptly influenced statewide recommendations for Phytophthora disease management in Wisconsin production of potatoes and vegetables.

A second program emphasis is on species distribution and occurrence of pathogenic Alternaria affecting potato.  Preliminary studies confirmed the presence of A. alternata in late season epidemics of early blight in northern Wisconsin.  Speciation of Alternaria throughout the production season at several regions of concentrated potato production in Wisconsin is being undertaken to further characterize the pathogen profile.  Additionally, sub-populations of Alternaria spp. collected from potatoes were partially resistant to the commonly-used fungicide active ingredient, azoxystrobin.  Mechanisms of fungicide resistance can differ between species.  As such, species determination may aid in regional or field-level tailoring of fungicide programs for enhanced disease control.  Early blight, caused by A. solani, is present every year in Wisconsin and can, if unmanaged, cause significant yield loss and reduction in tuber quality.   The importance and incidence of brown spot, caused by A. alternata, is poorly understood in Wisconsin at this time.  Our research addresses efficacy of novel fungicides and fungicide programs for more immediate application and support of grower needs, as well exploring pathogen ecological factors which may influence longer term disease management solutions.

A final area of research emphasis is the investigation of component inputs and development of integrated disease management programming in potato systems to reduce reliance upon soil fumigation in managing key soilborne diseases.  Our research approaches have included evaluation of disease control with reduced rates, alternative formulations, and in-line versus broadcast applications of soil fumigants such as chloropicrin and metam sodium to reduce quantity of soil-applied chemical.  Preliminary work suggests similar efficacy of some in-line-applied fumigants compared to broad-cast fumigants, offering a reduction in chemical use, and off-target and negative environmental and human health effects.   At-plant applications of nematicidal and fungicidal materials, potato vine removal, crop rotations, and cover crops have also been investigated with some positive preliminary results.  Soilborne diseases of potato such as potato early dying and common scab are especially challenging to manage and our research in this area of fumigation alternatives has been of great interest in regional industry and in academic circles.

As the UW-Extension Potato and Vegetable Pathologist, my program supports vegetable growers by providing research-based recommendations for controlling diseases during production and in storage.  My research program directly feeds into my extension work.  For more information about the vegetable extension program please visit the UW Vegetable Pathology website.

Along with a team of UW vegetable production scientists across departments, I extend knowledge through grower educational meetings, through our UW Vegetable Crop Updates Newsletter distributed online & by email, through direct email or phone consultations, and through one-on-one visits and discussion.  The connections between researchers and growers are strong in WI, with growers providing extensive intellectual and farm resources in contribution to world-class applied and basic agricultural research. Our Wisconsin Vegetable Team website is:  http://vegetables.wisc.edu/vegetable-team

• While I have no formal teaching appointment, I contribute expertise in pathogen ecology and integrated vegetable disease management. I choose to teach because I have great interest in cultivating a next generation of applied plant disease scientists, which is a field in high demand.
• PLP 875 Agricultural Oomycetes, Spring 2011

Google Scholar Profile

Ding, S., Rouse, D., Meinholz, K., Gevens, A.J.  2019.  Aerial concentrations of pathogens causing early blight and brown spot within susceptible potato fields.  FirstLook 17 Apr 2019.  Phytopathology.  https://doi.org/1o.1094/PHYTO-10-18-0381-R

Ding, S., Halterman, D., Meinholz, K., Gevens, A.J.  2019.  Distribution and stability of QoI fungicide resistance in populations of potato pathogenic Alternaria spp. in Wisconsin.  FirstLook 19 Mar 2019.  Plant Disease.    https://doi.org/10.1094/PDIS-11-18-1978-RE

Ding, S, Meinholz, K, Cleveland, K, Jordan, SA, Gevens, A.J. 2019.  Diversity and virulence of Alternaria spp. causing potato early blight and brown spot in Wisconsin.  Phytopathology 109(3):436-445.

Xue, D, Christenson, R, Genger, R, Gevens, A.J., Lankau, R.  2018.  Soil microbial communities reflect both inherent soil properties and management practices in Wisconsin potato fields.  American Journal of Potato Research.  95(6):696-708.

Marks, ME, Geske, AP, Weldon, W, Gadoury, DM, Gevens, A.J. 2018.  Reemergence of hop powdery mildew (Podosphaera macularis) in Wisconsin.  Plant Disease 102(7).

Culbreath, AK, Gevens, A.J., Stevenson, KL.  2018.  Relative effects of demethylation-inhibiting fungicides on late leaf spot of peanut.  Plant Health Progress 19(1).

Webster, B.J., Chen, Y., Gevens, A.J. 2018.  Impact of seed cutting and seed-borne inoculum on daughter tuber common scab and plant growth.  American Journal of Potato Research.  95(2):191-198.

Sanchez Perez, A., Jordan, S.A., Chen, Y., Gevens, A.J.  2017.  RB and Ph resistance genes in potato and tomato minimize risk for oospore production in the presence of mating pairs of Phytophthora infestans.  Accepted for Publication.  European Journal of Plant Pathology.  Vol. 149(4):  853-864.

Braun, S., Gevens, A.J., Charkowski, A.O., Allen, C., Jansky, S.  2017.  Potato common scab:  a review of the causal pathogen, management practices, screening methods, and host resistance.  American Journal of Potato Research.  Invited Review Article. DOI:  10.1007/s12230-017-9575-3.

Hansen, Z.R., Carlson, M.O., Everts, K.L., Fry, W.E., Gevens, A.J., Grünwald, N.J., Gugino, B.K., Knaus, B.J., Johnson, D.A., Johnson, S.B., Judelson, H.S., McGrath, M.T., Myers, K.L., Ristaino, J.B., Roberts, P.D, Secor, G.A., Smart, C.D.  2016.  Genetic variation within clonal lineages of Phytophthora infestans revealed through genotyping-by-sequencing, and implications for late blight epidemiology.  PlosOne 11(11):  e0165690.

Frost, K.E., Seidl Johnson, A.C., Gevens, A.J.  2016.  Survival of isolates of the US-22, US-23, and US-24 clonal lineages of Phytophthora infestans by asexual means in tomato seeds at cold temperatures.  Plant Disease 100:180-187.

Seidl Johnson, A.C., Frost, K.E., Rouse, D.I., Gevens, A.J. 2015. Effect of temperature on growth and sporulation of US-22, US-23, and US-24 clonal lineages of Phytophthora infestans and implications for late blight epidemiology. Phytopathology 4:449-459.

Fry, W.E., Birch, P.R.J., Hudelson, H.S., Grünwald, N.J., Danies, G., Everts, K.L., Gevens, A.J., Gugino, B.K., Johnson, D.A., Johnson, S.B., McGrath, M.T., Myers, K.L., Ristaino, J.B., Roberts, P.D., Secor, G., and Smart, C.D. 2015. Five reasons to consider Phytophthora infestans a reemerging pathogen. Phytopathology 7:966-981.

Seidl Johnson, A.C., Jordan, S.A., Gevens, A.J. 2015. Efficacy of organic and conventional fungicides and impact of application timing on control of tomato late blight caused by US-22, US-23, and US-24 isolates of Phytophthora infestans. Plant Disease 5:641-647.

Wang, Y., M.D. Ruark, A.J. Gevens, D.T. Caine, A.L. Raster, N.J. Goeser, and A.J. Bussan. 2015. Processing snap bean variety responses to applied nitrogen and irrigation in the North Central United States. Agronomy Journal 107:1401-1410.

Wharton, P.S., Kirk, W.W., Gevens, A.J., Nolte, P., Nolte, P., Dangi, S. 2015. First Report of Late Blight Caused by Phytophthora infestans Clonal Lineage US-23 on Potato in Idaho. Plant Disease 99:417.

Seidl Johnson, A.C., Gevens, A.J. 2014. Novel resistance in heirloom tomatoes and effectiveness of resistance in hybrids to Phytophthora infestans US-22, US-23, and US-24 clonal lineages. Plant Disease 98:761-765.

Seidl Johnson A.C., Gevens, A.J. 2014. Investigating the host range of the US-22, US-23, and US-24 clonal lineages of Phytophthora infestans on solanaceous cultivated plants and weeds. Plant Disease 98:754-760.

Seidl, A.C., Gevens, A.J. 2013. Characterization and distribution of three new clonal lineages of Phytophthora infestans causing late blight in Wisconsin from 2009 to 2012. American Journal of Potato Research 90:551-560.

Gevens, A.J., Seidl, A.C. 2013. First Report of Late Blight Caused by Phytophthora infestans Clonal Lineage US-24 on Potato (Solanum tuberosum) in Wisconsin. Plant Disease 97(3):152.

Fry, W. E., McGrath, M.T., Seaman, A., Zitter, T.A., McLeod, A, Danies, G., Small, I., Myers, K., Everts, K., Gevens, A.J., Gugino B., Johnson, S. Judelson, H., Ristaino, J., Roberts, P., Secor, G., Seebold, K., Snover-Clift, K., Wyenandt, C.A., Grünwald, N.J., and Smart, C.D. 2013. The 2009 Late Blight Pandemic in Eastern USA – causes and results. Plant Disease. 97(3): 296-306.

Gevens, A.J., Seidl, A.C. 2012. First Report of late blight caused by Phytophthora infestans clonal lineage US-22 on tomato and potato in Wisconsin. Plant Disease. 97(3): 423.

Gevens, A.J., Seidl, A.C. 2012. First Report of Late Blight caused by Phytophthora infestans Clonal Lineage US-23 on Tomato and Potato in Wisconsin, United States. Plant Disease 97:839.

Fry, W. E., McGrath, M.T., Seaman, A., Zitter, T.A., McLeod, A, Danies, G., Small, I., Myers, K., Everts, K., Gevens, A.J., Gugino B., Johnson, S. Judelson, H., Ristaino, J., Roberts, P., Secor, G., Seebold, K., Snover-Clift, K., Wyenandt, C.A., Grünwald, N.J., and Smart, C.D. 2012. The 2009 Late Blight Pandemic in Eastern USA – causes and results. APSnet Feature Article. Online.

Everts, K. L., Osborne, L., Gevens, A.J. , Vasquez, S. J., Gugino, B. K., Ivors, K., and Harmon, C. 2012. Extension Plant Pathology: Strengthening resources to continue serving the public interest. Phytopathology 102:652-655.

Ojiambo, P.S., Holmes, G.J., Britton, W., Keever, T., Adams, M.L., Babadoost, M., Bost, S.C., Boyles, R., Brooks, M., Damicone, J., Draper, M.A., Egel, D.S., Everts, K.L., Ferrin, D.M., Gevens, A.J., Gugino, B.K., Hausbeck, M.K., Ingram, D.M., Isakeit, T., Keinath, A.P., Koike, S.T., Langston, D., McGrath, M.T., Miller, S.A., Mulrooney, R., Rideout, S., Roddy, E., Seebold, K.W., Sikora, E.J., Thornton, A., Wick, R.L., Wyenandt, C.A., and Zhang, S. 2011. Cucurbit downy mildew ipmPIPE: a next generation web-based interactive tool for disease management and extension outreach. Online. Plant Health Progress doi:10.1094/PHP-2011- 0411-01-RV.

Zhang, S., Klassen, W., Mo, X., Ji, P., Gevens, A.J. 2011. Evaluation of Acibenzolar-S-methyl and silicic acid for control of Phytophthora blight caused by Phytophthora capsici in squash. Proceedings of the Florida State Horticultural Society. 124:154-161.

Jordan, S.A, Mailhot, D.J., Gevens, A.J., Marois, J.J., Wright, D.L., Harmon, C.L., and Harmon, P.F. 2010. Characterization of kudzu (Pueraria spp.) resistance to Phakopsora pachyrhizi, the causal agent of soybean rust. Phytopathology 100(9):941-948.

Maia, G.S., Gevens, A.J. 2009. Characterization of cucurbit powdery mildew in north Florida. Proceedings of the Florida State Horticultural Society 122: 247-250.

Gevens, A. J., Maia, G.S., Jordan, S.A. 2009. First Report of Powdery Mildew Caused by Golovinomyces cichoracearum on Crotalaria juncea (‘Tropic Sun’ Sunn hemp). Plant Disease. 93(4)427.

Gevens, A. J., Nequi, N., Vitoreli, A., Marois, J. J., Wright, D. L., Harmon, C. L., Harmon, P. F. 2008. First Report of Soybean Rust Caused by Phakopsora pachyrhizi on Erythrina herbacea (Coral bean). Plant Disease. 92(10)1472.

Gevens, A. J., Donahoo, R. S., Lamour, K. H., and Hausbeck, M. K. 2008. Characterization of Phytophthora capsici causing foliar and pod blight of snap bean in Michigan. Plant Disease 92(2)201-209.

Gevens, A. J., Donahoo, R. S., Lamour, K. H., and Hausbeck, M. K. 2007. Characterization of Phytophthora capsici from Michigan surface irrigation water. Phytopathology 97(4)421-428.

Gevens, A. J., Ando, K., Lamour, K. H., Grumet, R., and Hausbeck, M. K. 2006. A detached cucumber fruit method to screen for resistance to Phytophthora capsici and effect of fruit age on susceptibility to infection. Plant Disease 90(10)1276-1282.

Boddu, J., Svabek, C., Sekhon, R., Gevens, A. J., Nicholson, R. L., Jones, A. D., Pedersen, J. F., Gustine, D. L., and Chopra, S. 2004. Expression of a putative flavonoid 3’-hydroxylase in sorghum mesocotyls synthesizing 3-deoxyanthocyanidin phytoalexins. Physiological and Molecular Plant Pathology 65:101-113.

Chopra, S., Gevens, A. J., Svabek, C., Wood, K. V, Peterson, T., and Nicholson, R. L. 2002. Excision of the Candystripe 1 transposon from a hyper-mutable Y1-cs allele shows that the sorghum Y1 gene controls the biosynthesis of both 3-deoxyanthocyanidin phytoalexins and phlobaphene pigments. Physiological and Molecular Plant Pathology 60:321-330.

Aguero M. E., Gevens, A. J., Nicholson, R. L. 2002. Interaction of Cochliobolus heterostrophus with phytoalexin inclusions in Sorghum bicolor. Physiological and Molecular Plant Pathology 61:267-271.

Gevens, A. J., Carver, T. L. W., Thomas, B. J., Nicholson, R. L. 2001. Visualization and partial characterization of the ECM of Pestalotia malicola on artificial and natural substrata. Physiological and Molecular Plant Pathology 58:277-285.

Gevens, A. J., Nicholson, R. L. 2000. In This Issue “Cutin composition: A subtle role for fungal cutinase?” Physiological and Molecular Plant Pathology 57:43-45.