James Haudenshield,

Email: jsh1@illinois.edu
Phone: (217) 244-3257

PUBLICATIONS:

• 2015: Weems, J., Haudenshield, J. S., Bond, J., Hartman, G., Ames, K., and Bradley, C. A. 2015. Effect of fungicide seed treatments on Fusarium virguliforme infection of soybean and development of sudden death syndrome. Canadian Journal of Plant Pathology 37:435-447. [link] [view abstract]
  Sudden death syndrome (SDS), caused by Fusarium virguliforme (Fv), is a major yield-limiting disease of soybean in North America. Infection of soybean seedling roots by Fv results in severe root damage; therefore, fungicide seed treatments could potentially reduce these early-season infections and reduce severity of foliar symptoms that typically occur later in the season. Multiple fungicide seed treatment combinations were evaluated for their effects on Fv infection, DNA concentrations in roots, soybean root development, and SDS development in the field, greenhouse and laboratory trials. Several seed treatments decreased root disease symptoms compared with the non-treated inoculated control in the laboratory assay, and the biological seed treatment, Bacillus pumilus, significantly decreased seedling development and increased SDS root disease compared with the non-treated inoculated control. In the greenhouse, Fv DNA concentrations in roots were reduced by a treatment combining mefenoxam + thiophanate-methyl + azoxystrobin + Bacillus pumilus + prothioconazole + fludioxonil compared with the non-treated control; however, the reduction in Fv DNA did not improve root growth or decrease SDS symptoms compared with the non-treated control. Field trials were conducted in Valmeyer, IL in 2008 and in Urbana, IL in 2008 and 2009. Seed treatments had no effect on the concentration of Fv DNA in soybean roots and had very little effect on root morphology. At the Valmeyer location, most seed treatments significantly decreased SDS symptoms compared with the control. In summary, no consistent, significant effects of the seed treatments evaluated in this study on SDS or Fv root infection were observed. Therefore, soybean growers should continue to utilize other practices for SDS management until new seed treatments with consistent efficacy in controlling SDS are available.
  
  
  
• 2015: Murithi, H. H., Beed, F., Soko, M., Haudenshield, J. S., and Hartman, G. L. 2015. First Report of Phakopsora pachyrhizi on soybean causing rust in Malawi. Plant Disease 99:420. [link] [view abstract]
  Soybean rust (SBR), caused by Phakopsora pachyrhizi, has become established in Africa since the first report in Uganda in 1996 (2). The urediniospores, as windborne propagules, have infested new regions of Africa, initiating SBR in many countries, including Ghana and Democratic Republic of the Congo in 2007 (4) and Tanzania in 2014 (3). No refereed reports have been published about rust in Malawi, but some people have indicated that soybean rust may have been observed as early as 2008. Typical symptoms and signs of SBR, including leaf yellowing and tan, sporulating uredinia, were observed on soybean in May 2014 during field surveys in the major soybean-growing areas of Malawi, including the central (Dowa, Mchinji, and Kasungu) and southern (Thyolo) regions in nine out of 12 sites surveyed. When microscopically examined, urediniospores were elliptical, echinulate, and hyaline to pale yellowish brown. Leaves exhibiting sporuliferous uredinia were sent by APHIS permit to the University of Illinois. To confirm the pathogen, symptomatic soybean leaf tissue of approximately 1 cm2 was excised from each of the samples, and DNA was extracted using the FastDNA Spin Kit (MP Biomedicals, Solon, OH), with further purification using the MicroElute DNA Clean-up Kit (Omega Bio-Tek, Norcross, GA). The resulting DNA was analyzed by quantitative PCR using published Taqman assays for P. pachyrhizi and P. meibomiae, with a multiplexed exogenous internal control reaction to validate negative results (1). P. pachyrhizi DNA was detected in excess of 180,000 genome equivalents/cm2 in all samples, indicating a substantial infection. P. meibomiae DNA was determined to be absent from all samples, within the limit of quantification of ~2 pg DNA/cm2. Urediniospores dislodged from three leaves and inoculated onto susceptible soybean cultivar Williams 82 produced tan lesions after 2 weeks of incubation in a detached-leaf assay. This is the first confirmed report of P. pachyrhizi causing rust on soybean in Malawi, putting at risk 14,000 ha currently under soybean production. The reports of soybean rust in Malawi and adjoining countries will alter soybean production practices and research interests. In some cases, foliar application of fungicides has increased and planting dates have been changed to avoid conditions that are most conducive for rust development. Efforts to understand the virulence and genetic diversity of the pathogen in the region are needed in order to develop and deploy resistant cultivars.
  
  
  
• 2015: Hartman, G. L., Bowen, C. R., Haudenshield, J. S., Fox, C., Cary, T. R., and Diers, B. W. 2015. Evaluation of disease and pest damage on soybean cultivars released from 1923 through 2008 under field conditions in Central Illinois. Agronomy Journal 107:2373-2380. [link] [view abstract]
  Diseases and pests of soybean [Glycine max (L.) Merr.] often reduce soybean yields. Targeted breeding that incorporates known genes for resistance and non-targeted breeding that eliminates susceptible plants in breeding populations reduces the impact of soybean pathogens and pests. Maturity group (MG) III soybean cultivars released from 1923 through 2008 were grown in three field environments to determine if disease and insect ratings were associated with year of cultivar release. Disease and pest ratings were evaluated on 40 soybean cultivars at one location (Urbana, IL) planted in two rotation treatments in 2010 and on 59 cultivars in two locations (Urbana and Arthur) in 2011. During the season, foliar disease symptoms and insect foliar feeding damage were recorded. At harvest maturity, stem diseases were assessed. In at least one environment, foliar incidence reached 100% for bacterial diseases, brown spot (Septoria glycines Hemmi), and insect foliar feeding damage and 100% incidence for anthracnose [Colletotrichum truncatum (Schwein.) Andrus & W.D. Moore], Cercospora stem blight (Cercospora kikuchiiT. Matsumoto & Tomoy.), and charcoal rot [Macrophomina phaseolina (Tassi) Goid.] on stems for all cultivars. For the nine different disease and pest severity assessments in 2010, seven had a significant (P < 0.05) negative correlation to year of cultivar release indicating that cultivars more recently released had lower severity ratings than cultivars with older release dates. This study demonstrated that incidence and severity of diseases were less pronounced on more newly-released soybean cultivars, showing that decades of breeding has resulted in increased disease resistance in modern soybean cultivars.
  
  
  
• 2015: Haudenshield, J. S., and Hartman, G. L. 2015. Archaeophytopathology of Phakopsora pachyrhizi, the soybean rust pathogen. Plant Disease 99:575-579. [download] [view abstract]
  Herbarium specimens are useful to compare attributes of the past to attributes of today and predictions into the future. In this study, herbarium specimens from 1887 to 2006 were used to identify Phakopsora pachyrhizi and P. meibomiae, the two known fungal species that cause soybean rust. Historically, these two species differed in geographic distribution, with P. pachyrhizi confined to Asia and Australia, and P. meibomiae confined to the Americas. In our analyses, herbarium specimens were used to determine whether it was possible to extract adequate useful DNA from the fungal structures. If present, quantitative PCR primers specific to P. pachyrhizi, P. meibomiae, or to a third group inclusive of many rust species could be used to speciate the fungus. Of the 38 archival specimens, 11 were positive for P. pachyrhizi, including a 1912 specimen from Japan; 15 were positive for P. meibomiae, including a 1928 specimen from Brazil and two 1923 specimens from the Philippines; and 12 (including all African accessions) were negative for both species. Five specimens were positive in the more inclusive rust assay; all had been labeled as P. pachyrhizi and none were on soybean. These results demonstrate the feasibility of DNA genotyping in archaeophytopathological investigations.
  
  
  
• 2015: Yang, H.-C., Haudenshield, J. S., and Hartman, G. L. 2015. Multiplex real-time PCR detection and differentiation of Colletotrichum species infecting soybean. Plant Disease 99:1559-1568. [download] [view abstract]
  Colletotrichum species are fungal plant pathogens of worldwide significance. Colletotrichum species were isolated from soybean with anthracnose symptoms in five states in the United States from 2009 to 2013. Among 240 isolates collected, four Colletotrichum species were initially identified by morphological and sequence analysis, including C. chlorophyti, C. incanum, C. truncatum, and Colletotrichum sp. (henceforth Glomerella glycines, the name of its sexual state). To increase diagnostic efficiency and accuracy, real-time multiplex PCR assays based on a double-stranded DNA-binding dye coupled with dissociation curve analysis were designed, using a region of the cytochrome c oxidase subunit 1 (cox1) gene to discern these four Colletotrichum species. Two sets of duplex, real-time PCR assays were established and species differentiation was based upon amplicon melting point temperatures (Tm) in the dissociation curve analysis. The Set 1 duplex assay distinguished C. chlorophyti and G. glycines, and the Set 2 duplex assay distinguished C. incanum and C. truncatum. Successful detection was achieved with as little as 1 pg DNA. The assays were especially useful for differentiating C. chlorophyti, C. incanum, and C. truncatum, which have similar morphological features. Colletotrichum gloeosporioides, another pathogen associated with soybean anthracnose, was not resolved from G. glycines by the melting curve analysis. The two duplex real-time PCR assays were used to screen more than 200 purified Colletotrichum isolates, showing that they were rapid and effective methods to detect and differentiate Colletotrichum species infecting soybean.
  
  
  
• 2015: Kandal, Y. R., Haudenshield, J. S., Srour, A. Y., Islam, K. T., Fakhoury, A. M., Chilvers, M. I., Wang, J., Santos, P., Hartman, G. L., Malvick, D. K., Floyd, C. M., Mueller, D. S., and Leandro, L. F. S. 2015. Multi-laboratory comparison of quantitative PCR assays for detection and quantification of Fusarium virguliforme from soybean roots and soil. Phytopathology 105:1601-1611. [download] [view abstract]
  The ability to accurately detect and quantify Fusarium virguliforme, the cause of sudden death syndrome (SDS) in soybean, in samples such as plant root tissue and soil is extremely valuable for accurate disease diagnoses and to address research questions. Numerous quantitative real-time polymerase chain reaction (qPCR) assays have been developed for this pathogen but their sensitivity and specificity for F. virguliforme have not been compared. In this study, six qPCR assays were compared in five independent laboratories using the same set of DNA samples from fungi, plants, and soil. Multicopy gene-based assays targeting the ribosomal DNA intergenic spacer (IGS) or the mitochondrial small subunit (mtSSU) showed relatively high sensitivity (limit of detection [LOD] = 0.05 to 5 pg) compared with a single-copy gene (FvTox1)-based assay (LOD = 5 to 50 pg). Specificity varied greatly among assays, with the FvTox1 assay ranking the highest (100%) and two IGS assays being slightly less specific (95 to 96%). Another IGS assay targeting four SDS-causing fusaria showed lower specificity (70%), while the two mtSSU assays were lowest (41 and 47%). An IGS-based assay showed consistently highest sensitivity (LOD = 0.05 pg) and specificity and inclusivity above 94% and, thus, is suggested as the most useful qPCR assay for F. virguliforme diagnosis and quantification. However, specificity was also above 94% in two other assays and their selection for diagnostics and research will depend on objectives, samples, and materials used. These results will facilitate both fundamental and disease management research pertinent to SDS.
  
  
  
• 2014: Murithi, H. H., Madata, C. S., Haudenshield, J. S., and Hartman, G. L. 2014. First report of Phakopsora pachyrhizi on soybean causing rust in Tanzania. Plant Disease 98:1586. [link] [view abstract]
  Phakopsora pachyrhizi Syd. was reported on legume hosts other than soybean in Tanzania as early as 1979 (1). Soybean rust (SBR), caused by P. pachyrhizi, was first reported on soybean in Africa in Uganda in 1996 (3), and its introduction into Africa was proposed to occur through urediniospores blowing from western India to the African east coastal areas by moist northeast monsoon winds (4). The fungus rapidly spread and was reported on soybean in South Africa in 2001, in western Cameroon in 2003, and in Ghana and the Democratic Republic of the Congo in 2007 (5). A second species causing SBR on soybean, P. meibomiae, has not been reported in Africa or elsewhere, outside of the Americas. From 2012 to 2014, symptomatic leaf samples were collected in the major soybean growing areas of the Tanzanian Southern Highlands (Iringa, Mbeya, and Ruvuma regions). Symptoms of SBR included yellowing of leaves and tan sporulating lesions. These symptoms were observed at flowering through seed maturity. From fields surveyed in 2012, 2013, and 2014, SBR was observed in 5 of 14, 7 of 11, and 14 of 31 fields, respectively. Some of the leaves sampled had up to 80% of the leaf area affected. When microscopically examined, urediniospores were elliptical, echinulate, and hyaline to pale yellowish brown. In 2014, sporuliferous uredinia were observed on leaf material collected from the Iringa and Ruvuma regions of Tanzania, and a subset of these samples was sent by APHIS permit to the University of Illinois. To confirm the pathogen, symptomatic soybean leaf tissue of approximately 1 cm2 was excised from each of the samples, and DNA was extracted using the FastDNA Spin Kit (MP Biomedicals, Solon, OH), with further purification using the MicroElute DNA Clean-up Kit (Omega Bio-Tek, Norcross, GA). The DNA was subjected to quantitative PCR using published Taqman assays for P. pachyrhizi, P. meibomiae, and a multiplexed exogenous internal control reaction to validate negative results (2). P. pachyrhizi DNA was detected in excess of 66,000 genome equivalents/cm2 in all samples, and P. meibomiae DNA was determined to be absent from all samples (limit of quantification ~2 pg DNA/cm2). Free surviving urediniospores were dislodged from 12 samples and inoculated onto susceptible soybean cultivar Williams 82, which produced sporulating SBR lesions after 2 weeks of incubation in a detached-leaf assay. Thus, Koch's postulates were completed. This is the first report of P. pachyrhizi causing rust on soybean in Tanzania. In vivo cultures have been established from most of these samples, and ongoing research includes an evaluation of the P. pachyrizi virulence on a differential set, and characterization of the genetic diversity.
  
  
  
• 2014: Yang, H.-C., Haudenshield, J. S., and Hartman, G. L. 2014. Colletotrichum incanum sp. nov., a curved-conidial species causing soybean anthracnose in the USA. Mycologia 106:32-42. [link] [view abstract]
  Soybean anthracnose is caused by a number of species of Colletotrichum that as a group represent an important disease that results in significant economic losses. In the current study, Colletotrichum species were isolated from soybean petioles and stems with anthracnose symptoms from soybean fields in Illinois. Multigene sequence phylogenic analysis, combining rDNA internal transcribed spacer, actin, β-tubulin, glyceraldehyde-3-phosphate dehydrogenase and histone H3 gene regions, revealed a group of isolates collected in this study to be distinct from other established Colletotrichum species. This new group was phylogenetically closer to C. liriopes, C. tofieldiae and C. verruculosum than to C. truncatum, another species with curved conidia commonly found on soybean. A representative isolate from this new group was used to examine its morphology, cultural characteristics and pathogenicity to soybean; it was found to differ from C. truncatum in colony culture characteristics and sizes of conidia and appressoria. As a result of the molecular phylogenetic, morphological and pathogenicity analyses, we named this species Colletotrichum incanum. Of the 84 Colletotrichum isolates collected from soybean petioles, 40 were C. incanum, indicating that this species may commonly occur.
  
  
  
• 2012: Yang, Y.-C., Haudenshield, J. S., and Hartman, G. L. 2012. First report of Colletotrichum chlorophyti causing soybean anthracnose. Plant Dis. 96:1699. [link] [view abstract]
  Anthracnose of soybean [Glycine max (L.) Merr.] is caused by several Colletotrichum spp. (4). Petiole samples were collected from Alabama, Mississippi, and Illinois in 2009. Diseased tissues suspected of being caused by Colletotrichum were cut into 1- to 2-cm lengths, surface-disinfested, and placed on water agar. Pure cultures obtained by picking single spores from sporulating acervuli on tissue or hyphal tips on agar were transferred to acidic potato dextrose agar (APDA) at 24 ±1°C under 12-h cool-white fluorescent lighting. Isolates were grouped by morphological characteristics. One group consisting of six isolates (four from IL and one each from AL and MS) did not morphologically match any reported Colletotrichum spp. causing soybean anthracnose but matched the description of C. chlorophyti S. Chandra & Tandon (1,2). On APDA, colonies were initially pink, turning black after several days with smooth margins and no aerial mycelium. Conidial masses were light salmon in color. Conidia ranged from 15.5 to 21.3 μm long (mean 18.0 μm) × 2.5 to 4.3 wide (mean 3.3 μm) (n = 200). They were curved with tapered ends and a truncated base, aseptate, and hyaline. Chlamydospores were dark brown, clustered or chained together, and 5 to 12 μm wide (n = 30). Setae were straight, dark brown, and septate. Appressoria and perithecia were absent. Soybean plants (cv. Williams 82) at the V2 to V3 stage were atomized with a suspension of fragmented mycelia (40 mg/ml) using one isolate from IL. Plants were kept moist (>90% relative humidity) for 48 h in the dark, then transferred to normal growing conditions. Three days post-inoculation, younger trifoliolate leaf margins and intra- and interveinal lesions were necrotic surrounded by slight chlorosis. Isolations were obtained from symptomatic leaves and confirmed as C. chlorophyti by morphological characteristics. Further comparisons were completed with one isolate (IL1A or BPI 884117) by PCR and BLAST sequencing analyses of the partial ITS rDNA region, actin, β-tubulin, GAPDH, and histone H3 genes (2) (GenBank Accession Nos. JX126475, JX126476, JX126477, JX126478, and JX126479, respectively). The results showed high identity of all the five sequences to two C. chlorophytiisolates, IMI 103806 and CBS 142.79 (Accession Nos. GU227894/GU227895 in ITS = 100%, GU227992/GU227993 in actin = 99%, GU228188/GU228189 in β-tubulin = 99%, GU228286/GU228287 in GAPDH = 99% and 96%, respectively, and GU228090/GU228091 in histone H3 = 99%). Soybean anthracnose, commonly caused by C. truncatum, has curved and truncated conidia that are longer than C. chlorophyti. In addition, the two are distinguished by chlamydospores and lack of appressoria in C. chlorophyti combined with differences in multigene sequence analysis. Isolates of C. chlorophyti were reported to infect Chlorophytum sp. (Liliaceae) in India and Stylosanthes hamate in Australia (3). To our knowledge, there are no previous reports of this species in the United States or of it infecting soybean worldwide (3). This report describes C. chlorophyti as a novel incitant of soybean anthracnose.
  
  
  
• 2012: Vittal, R., Haudenshield, J. S., and Hartman, G. L. 2012. A multiplexed immunofluorescence method identifies Phakopsora pachyrhizi urediniospores and determines their viability. Phytopathology 102:1143-1152. [download] [view abstract]
  Soybean rust, caused by Phakopsora pachyrhizi, occurs concomitantly wherever soybean is grown in the tropical and subtropical regions of the world. After reports of its first occurrence in Brazil in 2001 and the continental United States in 2004, research on the disease and its pathogen has greatly increased. One area of research has focused on capturing urediniospores, primarily by rain collection or wind traps, and detecting them either by microscopic observations or by immunological or molecular techniques. This system of detection has been touted for use as a potential warning system to recommend early applications of fungicides. One shortcoming of the method has been an inability to determine whether the spores are viable. Our study developed a method to detect viable P. pachyrhizi urediniospores using an immunofluorescence assay combined with propidium iodide (PI) staining. Antibodies reacted to P. pachyrhizi and other Phakopsora spp. but did not react with other common soybean pathogens or most other rust fungi tested, based on an indirect immunofluorescence assay using fluorescein isothiocyanate-labeled secondary antibodies. Two vital staining techniques were used to assess viability of P. pachyrhizi urediniospores: one combined carboxy fluorescein diacetate (CFDA) and PI, and the other utilized (2-chloro-4-[2,3-dihydro-3-methyl-(benzo-1,3-thiazol-2-yl)-methylidene]-1-phenylquinolinium iodide] (FUN 1). Using the CFDA-PI method, viable spores stained green with CFDA and nonviable spores counterstained red with PI. Using the FUN 1 method, cylindrical intravacuolar structures were induced to form within metabolically active urediniospores, causing them to fluoresce bright red to reddishorange, whereas dead spores, with no metabolic activity, had an extremely diffused, faint fluorescence. An immunofluorescence technique in combination with PI counterstaining was developed to specifically detect viable P. pachyrhizi urediniospores. The method is rapid and reliable, with a potential for application in forecasting soybean rust based on the detection of viable urediniospores.
  
  
  
• 2011: Haudenshield, J. S. and Hartman, G.L. 2011. Exogenous controls increase negative call veracity in multiplexed, quantitative PCR assays for Phakopsora pachyrhizi. Plant Disease 95: 343-352. [download] [view abstract]
  Quantitative polymerase chain reaction (Q-PCR) utilizing specific primer sequences and a fluorogenic, 5′-exonuclease linear hydrolysis probe is well established as a detection and identification method for Phakopsora pachyrhizi and P. meibomiae, two rust pathogens of soybean. Because of the extreme sensitivity of Q-PCR, the DNA of single urediniospores of these fungi can be detected from total DNA extracts of environmental samples. However, some DNA preparations unpredictably contain PCR inhibitors that increase the frequency of false negatives indistinguishable from true negatives. Three synthetic DNA molecules of arbitrary sequence were constructed as multiplexed internal controls (ICs) to cull false-negative results by producing a positive signal to validate the PCR process within each individual reaction. The first two, PpaIC and PmeIC, are a single-stranded oligonucleotide flanked by sequences complementary to the primers of either the P. pachyrhizi or P. meibomiae primary assay but hybridizing to a unique fluorogenic probe; the third contains unique primer- and probe-binding sequences, and was prepared as a cloned DNA fragment in a linearized plasmid. These ICs neither qualitatively nor quantitatively affected their primary assays. PpaIC and PmeIC were shown to successfully identify false-negative reactions resulting from endogenous or exogenous inhibitors, and can be readily adapted to function in a variety of diagnostic Q-PCR assays; the plasmid was found to successfully validate true negatives in similar Q-PCR assays for other soybean pathogens, as well as to function as a tracer molecule during DNA extraction and recovery.
  
  
  
• 2010: Soria-Guerra R.E., Rosales-Mendoza S., Chang S., Haudenshield J.S., Zheng D., Rao S.S., Hartman G.L., Ghabrial S.A., and Korban S.S. 2010. Identifying differentially expressed genes in leaves of Glycine tomentella in the presence of the fungal pathogen Phakopsora pachyrhizi. Planta 232:1181–1189. [link]
  
  
• 2010: Soria-Guerra R.E., Rosales-Mendoza S., Chang S., Haudenshield J.S., Padmanaban A., Rodriguez-Zas S., Hartman G.L., Ghabrial S.A., and Korban S.S. 2010. Transcriptome analysis of resistant and susceptible genotypes of Glycine tomentella during Phakopsora pachyrhizi infection reveals novel rust resistance genes. Theor Appl Genet 120:1315–1333. [link]
  
  
• 2010: Bradley, C., Hines, R., Haudenshield, J.S., Hartman, G.L. 2010. First report of soybean rust, caused by Phakopsora pachyrhizi, on kudzu (Pueraria montana var. lobata) in Illinois. Plant Disease 94:477. [link] [view abstract]
  Soybean rust, caused by Phakopsora pachyrhizi Syd., first was observed in the continental United States during 2004 on soybean (Glycine max (L.) Merr.) in Louisiana (4), and on kudzu (Pueraria montana (Lour.) Merr. var. lobata (Willd.) Maesen & Almeida) in Florida (2). Kudzu is a leguminous weed that is prevalent in the southern United States with its range extending northward into other states including Illinois. In October 2009, a kudzu patch located in Pulaski County in southern Illinois was investigated for the presence of soybean rust. Twenty-five leaflets were collected, and the abaxial sides of leaflets were evaluated visually for the presence of uredinia with a dissecting microscope. Uredinia and urediniospores were found on two leaflets. When viewed with a compound microscope, urediniospores were hyaline, echinulate, and measured 20 × 25 μm. On the basis of uredinia and urediniospores, the disease tentatively was identified as soybean rust caused by P. pachyrhizi. To confirm the identification, one leaflet with pustules was assayed with a Soybean Rust QuickStix Diagnostic Kit (Envirologix, Portland, ME). For the other leaflet, the area of the pustule was excised (approximately 28 mm2) and an area of the leaflet at the margin on the opposite half of the leaflet with no visible pustule (approximately 54 mm2) was excised. DNA was extracted from the excised areas of the leaflet for confirmation by quantitative PCR (Q-PCR) using primers and probe specific to P. pachyrhizi and P. meibomiae (Arthur) Arthur (1). Both the QuickStix Diagnostic Kit and the Q-PCR confirmed the diagnosis as soybean rust caused by P. pachyrhizi. Q-PCR also suggested the presence of a nonsporulating latent rust infection on the same kudzu leaflet at the margin on the opposite side of the midrib. Soybean rust first was confirmed on soybean in Illinois in 2006 (3), but to our knowledge, this is the first observation of the disease on kudzu in the state. This report confirms that at least some kudzu plants in Illinois are susceptible to soybean rust and that latent kudzu infection may exist without outward signs of the fungus. Currently, this is the most northern observation of soybean rust on kudzu in North America. It is unknown what role, if any, Illinois kudzu will play in the epidemiology of soybean rust in the state. Since kudzu tops die after the first frost, there is no expectation of P. pachyrhizi to overwinter in Illinois on kudzu as it does in some states adjacent to the Gulf of Mexico.
  
  
  
• 2009: Hartman, G.L. and Haudenshield, J. S. 2009. Movement of Phakopsora pachyrhizi (soybean rust) spores by non-conventional means. European Journal of Plant Pathology 123:225–228. [link]
  
  
• 2007: Domier, L. L., Steinlage, T. A., Hobbs, H. A., Yang, Y., Herrera-Rodriguez, G., Haudenshield, J. S., McCoppin, N. K., and Hartman, G. L. 2007. Similarities in seed and aphid transmission among Soybean mosaic virus isolates. Plant Disease 91: 546-550. [download] [view abstract]
  Soybean mosaic virus (SMV) is an aphid- and seed-transmitted virus that infects soybean (Glycine max) plants and causes significant yield losses. Seed-borne infections are the primary sources of inoculum for SMV infections. The strain specificity of SMV transmission through seed and SMV-induced seed-coat mottling were investigated in field experiments. Six soybean plant introductions (PIs) were inoculated with eight SMV strains and isolates. Transmission of SMV through seed ranged from 0 to 43%, and isolate-by-soybean line interactions occurred in both transmission rates and percentages of mottled seeds. For example, SMV 746 was transmitted through 43% of seed in PI 229324, but was not transmitted through seed of PIs 68522, 68671, or 86449. In contrast, SMV 413 was transmitted through seed from all PIs. SMVs that were transmitted poorly by the Asian soybean aphid, Aphis glycines, also were transmitted poorly through seed. No predicted amino acid sequences within the helper-component protease or coat protein coding regions differentiated the two groups of SMV strains. The loss of aphid and seed transmissibility by repeated mechanical transmission suggests that constant selection pressure is needed to maintain the regions of the SMV genome controlling the two phenotypes from genetic drift and loss of function.