@article{bradshaw_braun_németh_paul_mitchell_crouch_thomas_pelt_takamatsu_kruse_et al._2026, title={Reassessment of the Erysiphe aquilegiae complex (Erysiphaceae)—resolution of a widespread and economically significant group of plant pathogens}, DOI={10.1016/j.funbio.2026.101717}, abstractNote={Species of powdery mildew in the Erysiphe aquilegiae complex infect a broad array of economically valuable plants. The increasing number of reports of infections from diverse hosts prompted the present comprehensive phylogenetic and taxonomic reassessment of the complex. Accurate species delimitation within the complex has been hindered by morphological similarity among members of the complex, their broad host associations, and insufficient resolution in rDNA (ITS+28S) analyses. As such, the species concepts within this complex have been controversial, ranging from recognition of a single widely circumscribed species, E. aquilegiae s. lat., to narrower concepts recognizing multiple species, usually based on associated host genera or host species. To better understand this complex, we have undertaken phylogenetic analyses based on eight loci: rDNA regions (ITS, 28S, IGS) and protein-coding genes (CAM, GAPDH, GS, RPB2, TUB). In total, we sequenced 163 collections from more than 20 countries, resulting in the deposition of over 600 sequences in GenBank. Based on these results, we have recognized two species with broad host ranges, E. aquilegiae s. str. (emend.) and E. hortensiae comb. nov., There are several host-specific species, including: E. aquilegiae-coeruleae sp. nov. E. clematidicola sp. nov. E. clematidis-montanae sp. nov., and E. thalictri sp. nov. The old name E. nitida is reintroduced for powdery mildew on Aconitum spp. and Delphinium spp. (Ranunculaceae tribe Delphinieae), which forms a well-supported clade outside the E. aquilegiae s. str. and E. hortensiae clade. Furthermore, E. parnassiae could be confirmed as a separate species belonging to the E. aquilegiae complex. The application of the rank forma for genetically established biological races forming subclades within the plurivorous species is discussed and conditions for the introduction of acceptable formae are outlined.}, journal={Fungal Biology}, author={Bradshaw, Michael and Braun, Uwe and Németh, Márk Z. and Paul, Andrew and Mitchell, James K. and Crouch, Uma and Thomas, Jackie and Pelt, Bailey and Takamatsu, Susumu and Kruse, Julia and et al.}, year={2026}, month={Jan} }
 @article{paul_crouch_mitchell_bradshaw_2025, title={<i>Erysiphe aesculi‐sylvaticae</i> sp. nov. Infecting North American <i>Aesculus</i> Species: A New Cryptic Species Provides Insights Into the Invasion Dynamics of an Important Fungal Pathogen}, volume={55}, DOI={10.1111/efp.70036}, abstractNote={ABSTRACT Aesculus is a genus of woody plant species that contains multiple ecologically and ornamentally important species. Powdery mildew is common on this host genus and is particularly virulent on the economically significant horse chestnut, Aesculus hippocastanum . Previously, all Erysiphe species found on Aesculus spp. were identified as Erysiphe flexuosa . Recent genomic research has indicated that powdery mildew species frequently show a high degree of host specificity which was not captured by traditional morphological approaches. As such, we proceeded to collect and sequence multiple regions of the powdery mildew genome to determine the causal agents of disease on different Aesculus spp. The results of our multilocus phylogenetic analyses revealed the existence of a genetically distinct species, which has been found only on Aesculus spp. native to North America. Erysiphe aesculi‐sylvaticae sp. nov. is proposed for this cryptic species. In the past 25 years, there have been multiple reports of an E. flexuosa epidemic on Aesculus hippocastanum in Europe, while E. aesculi‐sylvaticae has yet to be identified outside of the United States. The discovery of this new cryptic powdery mildew species as well as analysis of additional sequences from collections of E. flexuosa from North America, including from the type specimen collected in 1872, are discussed in detail with an emphasis on the implications for the co‐evolution, worldwide spread, and invasion dynamics of these powdery mildews. Future research should continue to collect and sequence powdery mildews on different Aesculus spp. to better understand the diversity and spread of these economically important pathogens.}, number={4}, journal={Forest Pathology}, author={Paul, Andrew and Crouch, Uma and Mitchell, James K. and Bradshaw, Michael}, year={2025}, month={Aug} }
 @article{crouch_bean_paul_thomas_bradshaw_2025, title={First Report of <i>Golovinomyces ambrosiae</i> on <i>Cirsium arvense</i> Worldwide}, volume={10}, DOI={10.1094/PDIS-05-25-0945-PDN}, abstractNote={Cirsium arvense, also known as Canada or creeping thistle, is a noxious perennial weed in North America that severely impacts native and agriculturally significant crops. Recent research has been focusing on the use of the rust Puccinia suaveolens as a biological control agent. In 2025, Canada thistles in a growth chamber on Centennial Campus of North Carolina State University (35.77405°N, 78.67579°W) became infected with powdery mildew. Leaves were completely covered with white mycelial growth. Morphologically, mycelium was amphigenous, effuse; hyphae flexuous, hyaline, septate, 4-6 µm wide; hyphal appressoria indistinct to nipple shaped, 5-7 µm diam.; conidiophores arising from the upper surface of the mother cell, straight, unbranched; foot-cells subcylindrical, (50-)78-94(-112) × 9-11 µm, followed by 1-3 shorter cells after foot cell; conidia hyaline, cylindrical-doliiform, lacking fibrosin bodies, (29-)33-35(-38) × 14-16(-20) µm, length/width ratio 2-2.3; germ tubes ± terminal, 22-32(-73) µm long, conidial appressoria club shaped, Euoidium type; chasmothecia were not observed. The anamorph of the specimen identified in this study was shown to be morphologically identical to Golovinomyces ambrosiae and had significant differences from the closely related G. latisporus in conidial shape and size as well as in the shape of the conidial appressoria. The two species can be differentiated in that G. ambrosiae has narrower and longer cylindrical-doliiform conidia with a length/width ratio that can be >2 versus G. latisporus with shorter and broad ellipsoid-ovoid, doliiform conidia with a length/ratio < 2 on average (1.3-1.9). Additionally, the conidial germ tubes of G. ambrosiae were short with typical Euoidium type, swollen tips while G. latisporus exhibits longer germ tubes often of the longitubus type (Qiu et al. 2020). Golovinomyces montagnei, which is a common pathogen for this host in Europe, has wider and longer conidia; (25-)30-45 × 15-23 μm (Braun and Cook 2012). We sequenced the ITS (GenBank Number: PV581748), IGS (PV584301), GAPDH (PV584324), GS (PV584325), and RPB2 (PV584332) regions with the following primer pairs: PM10 (Bradshaw and Tobin 2020) /PM2 (Cunnington et al. 2003), IGS-12a/NS1R (Carbone and Kohn, 1999), PMGAPDH1/PMGAPDH3R, GSPM2/GSPM3R, and PMRpb2_4/PMRpb2_6 (Bradshaw et al. 2022a). All regions sequenced aligned 100% with other G. ambrosiae specimens including FH00941245 (ON073878, ON361194, ON075631, ON119167, ON075691) and FH00941246 (ON073842, ON361187, ON075629, ON075689, ON119163). The specimen was deposited in the Larry F. Grand Mycological Herbarium (Voucher Number: NCSLG 25310). We confirmed pathogenicity using two uninfected Canada thistle plants. One plant was inoculated by touching diseased leaves to wet healthy leaves and then kept in the same growth chamber as the infected plants. The other plant was not inoculated and placed in a separate growth chamber as a control. Ten days after inoculation, typical powdery mildew symptoms and signs were observed. Powdery mildew was also observed spreading to multiple other Canada thistle plants in the growth chamber that held the inoculated plant. No symptoms were observed on the non-inoculated control plant. Golovinomyces montagnei and G. depressus have been reported to infect C. arvense from Europe (Bradshaw et al. 2024). Multiple reports have identified powdery mildew on C. arvense from Idaho, Washington, and Oregon as Erysiphe cichoracearum or Golovinomyces cichoracearum, but these names have been used broadly for a range of powdery mildew species (Newcombe and Nischwitz 2004; Dungan and Glawe 2007; Bradshaw et al. 2022b); both reports could have been referring to G. ambrosiae, G. montagnei or G. depressus. However, based on the present study, it is highly likely that they were referring to G. ambrosiae. Interestingly, from personal observations, the powdery mildew tended to infect the plant most heavily when the rust, P. suaveolens, was also present. This information is important for the agriculture industry where C. arvense is a major problem.}, journal={Plant Disease}, author={Crouch, Uma and Bean, Dan and Paul, Andrew and Thomas, Jacklyn and Bradshaw, Michael}, year={2025}, month={Jun} }
 @article{lagreca_crouch_paul_thomas_thompson_shaw_cubeta_braun_bradshaw_2025, title={Hidden treasures of herbaria - even small collections contain a wealth of diversity: the powdery mildews of the North Carolina State Larry F. Grand Mycological Herbarium}, volume={16}, DOI={10.3897/imafungus.16.156231}, abstractNote={The occurrence of cryptic species is well documented in fungi but the extent of their diversity is not fully understood. This study assessed the fungal diversity within a part of the Larry F. Grand Mycological Herbarium (NCSLG), a small, well-maintained collection at North Carolina State University, with a focus on the powdery mildew fungi (<i>Erysiphaceae</i>). <i>Erysiphaceae</i> were selected due to their economic impact as plant pathogens and availability of extensive DNA sequence data for multiple barcode loci. Our research objectives included determining the number of phylogenetic species compared with those identified morphologically, and to identify undescribed species. We generated sequence data for 220 of the 299 powdery mildew specimens (73% success rate) in the herbarium, which represented 60 species in 10 genera, collected from 134 host plant species. Our analyses revealed that ~83% (183/220) of the sequenced specimens had identifications that were incorrect and/or outdated based on current genus/species concepts. Additionally, four new species are described: <i>Erysipheamphicarpaeicola</i>, <i>E.ulmi-alatae</i>, <i>E.quercus-virginianae</i>, and <i>Takamatsuellagrandii</i>. A specimen deposited at NCSLG is designated as an epitype for <i>Phyllactinialiriodendri</i>, and a species of <i>Phyllactinia</i> identified on <i>Carpinuscaroliniana</i>, as well as multiple species infecting <i>Quercus</i> spp., likely represent additional undescribed species that require more data. This research highlights the critical role of herbarium collections in uncovering fungal biodiversity, and underscores the importance of preserving these valuable resources, particularly with the growing trend to discard herbaria due to financial and space constraints.}, journal={IMA Fungus}, author={LaGreca, Scott and Crouch, Uma and Paul, Andrew and Thomas, Jacklyn and Thompson, Jake and Shaw, Christian and Cubeta, Marc A. and Braun, Uwe and Bradshaw, Michael}, year={2025}, month={Jun} }
 @article{bradshaw_liu_crouch_thomas_shoukouhi_jin_liu_paul_braun_2025, title={Powdery mildews on <i>Fragaria </i>spp. and <i>Rubus </i>spp. - unravelling the phylogeny and taxonomy of economically relevant species within the intricate <i>Podosphaera aphanis </i>s. lat. complex}, volume={66}, DOI={10.47371/mycosci.2025.05.001}, abstractNote={Powdery mildews from the genus Podosphaera infect economically significant crops such as strawberries (Fragaria ×ananassa) and raspberries (Rubus idaeus). Until recently, these powdery mildews have been assigned to Podosphaera aphanis, which represents a complex of species. In the present analysis, selected taxa within Po. aphanis s. lat. have been subjected to morphological and ITS+28S rDNA phylogenetic examinations. We demonstrated that the powdery mildews on Fragaria and Rubus spp. do not pertain to Po. aphanis s. str. The new combination Podosphaera fragariae (≡ Oidium fragariae) is introduced for the powdery mildew on Fragaria ×ananassa, Potentilla spp. and Dasiphora fruticosa. Podosphaera fragariae is widespread in Asia and Europe, however, sequences obtained from specimens collected in South and North America belong to an unresolved group. All sequences obtained from specimens of powdery mildew on Rubus spp. group together in the phylogenetic tree. This suggests a separate species on Rubus spp. for which the new combination Podosphaera ruborum (≡ Oidium ruborum) is introduced. Podosphaera rubi-spectabilis sp. nov. is introduced for powdery mildews from western North America infecting Rubus spectabilis and R. ursinus. Additionally, Po. septentrionalis sp. nov. is introduced for powdery mildews in North America infecting Geum spp. and Agrimonia gryposepala.}, number={4}, journal={Mycoscience}, author={Bradshaw, Michael and Liu, Miao and Crouch, Uma and Thomas, Jacklyn and Shoukouhi, Parivash and Jin, Dan-Ni and Liu, Shu-Yan and Paul, Andrew and Braun, Uwe}, year={2025}, month={Jun}, pages={222–231} }