{"id":9292,"date":"2026-05-11T06:26:52","date_gmt":"2026-05-11T10:26:52","guid":{"rendered":"https:\/\/provost.ncsu.edu\/global-one-health-academy\/2026\/05\/11\/study-reveals-how-strawberries-were-ambushed-by-fungal-parasites\/"},"modified":"2026-06-24T16:54:28","modified_gmt":"2026-06-24T20:54:28","slug":"study-reveals-how-strawberries-were-ambushed-by-fungal-parasites","status":"publish","type":"post","link":"https:\/\/provost.ncsu.edu\/global-one-health-academy\/2026\/05\/11\/study-reveals-how-strawberries-were-ambushed-by-fungal-parasites\/","title":{"rendered":"GOHA Affiliate Member Co-Authors Study on How Strawberries Were Ambushed By Fungal Parasites"},"content":{"rendered":"\n\n\n\n\n

For Immediate Release<\/h2>\n
Michael Bradshaw<\/span>mjbradsh@ncsu.edu<\/a><\/div>\n\n\n\n
Matt Shipman<\/span>matt_shipman@ncsu.edu<\/a><\/div>\n<\/section>\n\n\n\n

Plant diseases often arise when the pathogens that cause disease are introduced into new territories where native plants don\u2019t recognize the pathogen and therefore may have minimal defenses against it. But there\u2019s another option.<\/p>\n\n\n\n

How often does the reverse happen: a plant gets introduced into areas where the pathogen already lurks in the soil \u2013 targeting other plant hosts native to the area \u2013 and then \u201cjumps\u201d to infect the newly introduced plant?<\/p>\n\n\n\n

A new finding regarding strawberries and raspberries encumbered with powdery mildew disease in North America, Europe and Asia suggests the latter happens more frequently than we thought.<\/p>\n\n\n\n

The study pinpoints the ancestral history of powdery mildew disease caused by different but related fungi. The findings could aid the understanding of how plant diseases arise.<\/p>\n\n\n\n

\u201cWe have this general idea that a pathogen originates in one spot, and then it spreads throughout the world. But what we\u2019re showing here is that\u2019s not always the case,\u201d said Michael Bradshaw, assistant professor of plant pathology at NC State and corresponding author of a paper describing the research.<\/p>\n\n\n\n

\u201cWhat happened in this case is that the pathogen co-evolved on one host pretty closely related to strawberries or raspberries over millions and millions of years, and then when strawberries or raspberries were introduced to the same area, the pathogen jumped hosts.\u201d<\/p>\n\n\n\n

As its name suggests, powdery mildew disease causes a white, powdery substance to cover host plants, stealing nutrients and retarding photosynthesis while keeping the host alive. Different species of this fungus affect different plants; wheat, hops, grapes and blueberries, among other plants, have been detrimentally affected by powdery mildew.<\/p>\n\n\n\n

In the study, Bradshaw and his colleagues examined historic and modern plant leaves plagued by powdery mildew. The collection included 70 samples from North America and Europe; some were more than 100 years old.<\/p>\n\n\n\n

The researchers performed genetic testing on fungal samples to trace the history and spread of powdery mildew disease. In North American samples, the powdery mildew Podosphaera shepherdiae<\/em> infects strawberries, while in Europe and Asia a related but different powdery mildew, Podosphaera fragariae<\/em>, plagues strawberries.<\/p>\n\n\n\n

\u201cIf you\u2019re looking under the microscope at these pathogens, the one that infects strawberries in North America looks very different from the one that infects strawberries in Europe,\u201d Bradshaw said. \u201cTo date, the powdery mildew from Europe still hasn\u2019t been found in North America, and vice versa. So that\u2019s kind of like the smoking gun: It\u2019s not one pathogen spreading throughout the world. These pathogens seem to be already present in these different places.\u201d<\/p>\n\n\n\n

The study also used molecular clock techniques to show that these two powdery mildew pathogens affecting strawberries on different continents split off from each other more than five million years ago.<\/p>\n\n\n\n

Both North American and European powdery mildew pathogens infect plants in the rosaceous family, which includes flowering plants related to roses, strawberries, raspberries, peaches and pears, among others.<\/p>\n\n\n\n

\u201cThese two pathogens were actually described over a hundred years ago, one of which was described on a plant native to North America,\u201d Bradshaw said.<\/p>\n\n\n\n

Bradshaw believes these findings \u2013 showing that pathogens can jump from a native plant to a newly introduced plant \u2013 can be generalized for most plant pathogens.<\/p>\n\n\n\n

He also predicts these pathogens will eventually spread the more traditional way \u2013 by traveling on plant material brought across the Atlantic Ocean \u2013 and attempt to live and thrive on a new continent.<\/p>\n\n\n\n

\u201cWill these two different organisms mate with each other? Will they infect strawberries more when they\u2019re both on the plant? Or will they compete with each other for the host\u2019s resources and cancel each other out?\u201d<\/p>\n\n\n\n

Bradshaw also plans to study more about the powdery mildew on wine grapes and wheat, two important crops affected by other powdery mildew species.<\/p>\n\n\n\n

The paper, \u201cGlobal Crop Introduction Drives Host Jumps, Turning Native Pathogens into Emerging Diseases<\/a>,\u201d appears in Proceedings of the National Academy of Sciences<\/em>. Funding was provided by the National Science Foundation under award number 2402193 and by the U.S. Department of Agriculture\u2019s National Institute of Food and Agriculture Research Capacity Fund (HATCH), project award number 7006142. This work was part of the Chancellor\u2019s Faculty Excellence Program in the Emerging Plant Disease and Global Food Security Cluster.<\/p>\n\n\n\n

Note to editors:<\/strong> The abstract of the paper follows.<\/p>\n\n\n\n

\u201cGlobal Crop Introduction Drives Host Jumps, Turning Native Pathogens into Emerging Diseases\u201d<\/strong><\/p>\n\n\n\n

Authors<\/em>: Uma Crouch, Andrew Paul, Ignazio Carbone, Uwe Braun, Bailey Pelt, Gerald Holmes, Susumu Takamatsu, Dan-Ni Jin, Shu- Yan Liu and Michael Bradshaw<\/p>\n\n\n\n

Published<\/em>: May 8, 2026 in Proceedings of the National Academy of Sciences<\/em><\/p>\n\n\n\n

DOI<\/em>: 10.1073\/pnas.2536984123<\/p>\n\n\n\n

Abstract:<\/strong> Global crop movement has traditionally been viewed as a major driver of emerging plant diseases through the introduction of pathogens into na\u00efve environments. Here we show that the reverse process, introducing crops into regions containing endemic pathogens already adapted to related native hosts, is an equally powerful but underrecognized mechanism of disease emergence. Using multilocus phylogeny, haplotype networks, split-tree analysis, and molecular clock dating of both fresh and century-old herbarium specimens, we reconstructed the global history of powdery mildews infecting strawberries and raspberries. We reveal that these fungi comprise ancient, geographically structured, host-specialized lineages rather than a single cosmopolitan species as previously assumed. North American lineages infecting strawberries (Podosphaera shepherdiae<\/em>) and Eurasian lineages infecting strawberries (P. fragariae<\/em>) trace their origins to native rosaceous hosts, predating modern agriculture by millions of years. Raspberry-infecting lineages showed similar patterns of local endemism and host association. These findings demonstrate that emerging plant diseases can arise not only when pathogens move globally, but also when non-native crops are introduced into landscapes containing long-established native pathogens. This work highlights the importance of taxonomic resolution and herbarium genomics for identifying the true origins of agricultural diseases and for understanding the evolutionary pathways that give rise to modern epidemics.<\/p>\n

This post was originally published<\/a> in NC State News.<\/em><\/p>","protected":false,"raw":"\n\n\n\n\n

For Immediate Release<\/h2>\n
Michael Bradshaw<\/span>mjbradsh@ncsu.edu<\/a><\/div>\n\n\n\n
Matt Shipman<\/span>matt_shipman@ncsu.edu<\/a><\/div>\n<\/section>\n\n\n\n

Plant diseases often arise when the pathogens that cause disease are introduced into new territories where native plants don\u2019t recognize the pathogen and therefore may have minimal defenses against it. But there\u2019s another option.<\/p>\n\n\n\n

How often does the reverse happen: a plant gets introduced into areas where the pathogen already lurks in the soil \u2013 targeting other plant hosts native to the area \u2013 and then \u201cjumps\u201d to infect the newly introduced plant?<\/p>\n\n\n\n

A new finding regarding strawberries and raspberries encumbered with powdery mildew disease in North America, Europe and Asia suggests the latter happens more frequently than we thought.<\/p>\n\n\n\n

The study pinpoints the ancestral history of powdery mildew disease caused by different but related fungi. The findings could aid the understanding of how plant diseases arise.<\/p>\n\n\n\n

\u201cWe have this general idea that a pathogen originates in one spot, and then it spreads throughout the world. But what we\u2019re showing here is that\u2019s not always the case,\u201d said Michael Bradshaw, assistant professor of plant pathology at NC State and corresponding author of a paper describing the research.<\/p>\n\n\n\n

\u201cWhat happened in this case is that the pathogen co-evolved on one host pretty closely related to strawberries or raspberries over millions and millions of years, and then when strawberries or raspberries were introduced to the same area, the pathogen jumped hosts.\u201d<\/p>\n\n\n\n

As its name suggests, powdery mildew disease causes a white, powdery substance to cover host plants, stealing nutrients and retarding photosynthesis while keeping the host alive. Different species of this fungus affect different plants; wheat, hops, grapes and blueberries, among other plants, have been detrimentally affected by powdery mildew.<\/p>\n\n\n\n

In the study, Bradshaw and his colleagues examined historic and modern plant leaves plagued by powdery mildew. The collection included 70 samples from North America and Europe; some were more than 100 years old.<\/p>\n\n\n\n

The researchers performed genetic testing on fungal samples to trace the history and spread of powdery mildew disease. In North American samples, the powdery mildew Podosphaera shepherdiae<\/em> infects strawberries, while in Europe and Asia a related but different powdery mildew, Podosphaera fragariae<\/em>, plagues strawberries.<\/p>\n\n\n\n

\u201cIf you\u2019re looking under the microscope at these pathogens, the one that infects strawberries in North America looks very different from the one that infects strawberries in Europe,\u201d Bradshaw said. \u201cTo date, the powdery mildew from Europe still hasn\u2019t been found in North America, and vice versa. So that\u2019s kind of like the smoking gun: It\u2019s not one pathogen spreading throughout the world. These pathogens seem to be already present in these different places.\u201d<\/p>\n\n\n\n

The study also used molecular clock techniques to show that these two powdery mildew pathogens affecting strawberries on different continents split off from each other more than five million years ago.<\/p>\n\n\n\n

Both North American and European powdery mildew pathogens infect plants in the rosaceous family, which includes flowering plants related to roses, strawberries, raspberries, peaches and pears, among others.<\/p>\n\n\n\n

\u201cThese two pathogens were actually described over a hundred years ago, one of which was described on a plant native to North America,\u201d Bradshaw said.<\/p>\n\n\n\n

Bradshaw believes these findings \u2013 showing that pathogens can jump from a native plant to a newly introduced plant \u2013 can be generalized for most plant pathogens.<\/p>\n\n\n\n

He also predicts these pathogens will eventually spread the more traditional way \u2013 by traveling on plant material brought across the Atlantic Ocean \u2013 and attempt to live and thrive on a new continent.<\/p>\n\n\n\n

\u201cWill these two different organisms mate with each other? Will they infect strawberries more when they\u2019re both on the plant? Or will they compete with each other for the host\u2019s resources and cancel each other out?\u201d<\/p>\n\n\n\n

Bradshaw also plans to study more about the powdery mildew on wine grapes and wheat, two important crops affected by other powdery mildew species.<\/p>\n\n\n\n

The paper, \u201cGlobal Crop Introduction Drives Host Jumps, Turning Native Pathogens into Emerging Diseases<\/a>,\u201d appears in Proceedings of the National Academy of Sciences<\/em>. Funding was provided by the National Science Foundation under award number 2402193 and by the U.S. Department of Agriculture\u2019s National Institute of Food and Agriculture Research Capacity Fund (HATCH), project award number 7006142. This work was part of the Chancellor\u2019s Faculty Excellence Program in the Emerging Plant Disease and Global Food Security Cluster.<\/p>\n\n\n\n

Note to editors:<\/strong> The abstract of the paper follows.<\/p>\n\n\n\n

\u201cGlobal Crop Introduction Drives Host Jumps, Turning Native Pathogens into Emerging Diseases\u201d<\/strong><\/p>\n\n\n\n

Authors<\/em>: Uma Crouch, Andrew Paul, Ignazio Carbone, Uwe Braun, Bailey Pelt, Gerald Holmes, Susumu Takamatsu, Dan-Ni Jin, Shu- Yan Liu and Michael Bradshaw<\/p>\n\n\n\n

Published<\/em>: May 8, 2026 in Proceedings of the National Academy of Sciences<\/em><\/p>\n\n\n\n

DOI<\/em>: 10.1073\/pnas.2536984123<\/p>\n\n\n\n

Abstract:<\/strong> Global crop movement has traditionally been viewed as a major driver of emerging plant diseases through the introduction of pathogens into na\u00efve environments. Here we show that the reverse process, introducing crops into regions containing endemic pathogens already adapted to related native hosts, is an equally powerful but underrecognized mechanism of disease emergence. Using multilocus phylogeny, haplotype networks, split-tree analysis, and molecular clock dating of both fresh and century-old herbarium specimens, we reconstructed the global history of powdery mildews infecting strawberries and raspberries. We reveal that these fungi comprise ancient, geographically structured, host-specialized lineages rather than a single cosmopolitan species as previously assumed. North American lineages infecting strawberries (Podosphaera shepherdiae<\/em>) and Eurasian lineages infecting strawberries (P. fragariae<\/em>) trace their origins to native rosaceous hosts, predating modern agriculture by millions of years. Raspberry-infecting lineages showed similar patterns of local endemism and host association. These findings demonstrate that emerging plant diseases can arise not only when pathogens move globally, but also when non-native crops are introduced into landscapes containing long-established native pathogens. This work highlights the importance of taxonomic resolution and herbarium genomics for identifying the true origins of agricultural diseases and for understanding the evolutionary pathways that give rise to modern epidemics.<\/p>\n"},"excerpt":{"rendered":"

Plant pathogens don’t always spread from place to place. Sometimes they lie in wait.<\/p>\n","protected":false},"author":16,"featured_media":9293,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"source":"ncstate_wire","ncst_custom_author":"","ncst_show_custom_author":false,"ncst_dynamicHeaderBlockName":"ncst\/default-post-header","ncst_dynamicHeaderData":"{\"caption\":\"Microscopic image of the fungus powdery mildew that infects strawberries. The round structures are survival structures that help the fungus survive over the winter. In this image, these structures are releasing sac-like bodies that contain the spores. Fine, thread-like filaments surrounding them help the structures attach to the plant. Differences in color reflect different stages of development. Image by Andrew Paul.\",\"displayCategoryID\":3,\"showAuthor\":true,\"showDate\":true,\"showFeaturedVideo\":false}","ncst_content_audit_freq":"","ncst_content_audit_date":"","footnotes":"","_links_to":"","_links_to_target":""},"categories":[13],"tags":[11],"class_list":["post-9292","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-newswire","tag-_from-newswire-collection-481"],"displayCategory":null,"acf":[],"_links":{"self":[{"href":"https:\/\/provost.ncsu.edu\/global-one-health-academy\/wp-json\/wp\/v2\/posts\/9292","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/provost.ncsu.edu\/global-one-health-academy\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/provost.ncsu.edu\/global-one-health-academy\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/provost.ncsu.edu\/global-one-health-academy\/wp-json\/wp\/v2\/users\/16"}],"replies":[{"embeddable":true,"href":"https:\/\/provost.ncsu.edu\/global-one-health-academy\/wp-json\/wp\/v2\/comments?post=9292"}],"version-history":[{"count":1,"href":"https:\/\/provost.ncsu.edu\/global-one-health-academy\/wp-json\/wp\/v2\/posts\/9292\/revisions"}],"predecessor-version":[{"id":9295,"href":"https:\/\/provost.ncsu.edu\/global-one-health-academy\/wp-json\/wp\/v2\/posts\/9292\/revisions\/9295"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/provost.ncsu.edu\/global-one-health-academy\/wp-json\/wp\/v2\/media\/9293"}],"wp:attachment":[{"href":"https:\/\/provost.ncsu.edu\/global-one-health-academy\/wp-json\/wp\/v2\/media?parent=9292"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/provost.ncsu.edu\/global-one-health-academy\/wp-json\/wp\/v2\/categories?post=9292"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/provost.ncsu.edu\/global-one-health-academy\/wp-json\/wp\/v2\/tags?post=9292"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}