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Bacterial leaf streak (BLS) of corn caused by Xanthomonas vasicola pv. vasculorum was first reported in the United States in 2017. The biology and management of BLS are poorly understood. The objective of this work was to determine the effects of hybrids, foliar treatments, and infection conditions (timing, temperature, and inoculation site) on BLS of sweet corn. Field studies were conducted to determine if hybrid or foliar disease management treatments influenced BLS development and yield. Corn leaves were inoculated in plots with X. vasicola pv. vasculorum , and noninoculated plots were used for comparison. The leaf incidence and severity of BLS differed significantly among sweet corn hybrids, suggesting different levels of susceptibility to BLS. Grain yield was significantly reduced (14.7%) by BLS for one hybrid. The corn growth stage at the time of infection influenced BLS, with incidence and severity significantly greater after inoculation at stage V6 than at V9. Foliar application of Kocide, LifeGard, and Kocide and LifeGard significantly reduced leaf severity compared with nontreated controls in field studies. Kocide significantly reduced leaf incidence, but no treatments significantly increased yield versus controls. In comparisons of inoculation methods in a growth chamber, lesion length on leaves was significantly greater on stalk-inoculated than leaf-inoculated plants. Lesions developed on leaf-inoculated plants only at inoculation sites, whereas lesions developed on stalk-inoculated plants on multiple leaves. In controlled environments, lesion length on leaves was significantly greater at 21°C than at 27 and 32°C. This study expands our understanding of factors that influence the development and management of BLS of sweet corn., Competing Interests: The author(s) declare no conflict of interest.

Tar spot of corn ( Zea mays L.) is a significant disease in the United States and Canada caused by Phyllachora maydis , an obligate biotroph fungus. However, field research critical for understanding and managing the disease has been hindered by a need for methods to inoculate corn with P. maydis in field environments. In this study, we developed and demonstrated the efficacy of a method to initiate tar spot in field settings using inoculations of corn leaves with P. maydis inoculum that had been stored at -20°C for 10 months. Stromata of P. maydis were observed 19 days after inoculations in two field experiments, and stromata resulting from secondary spread were initially observed 39 to 41 days after the initial inoculations. Tar spot was not present in the fields beyond the inoculated areas or localized spread area, signifying that the establishment of initial disease resulted solely from inoculations. This study enhances our understanding of inoculation and infection of corn with P. maydis and tar spot development in field environments. The results will aid new research into understanding the corn tar spot pathosystem and improving management strategies., Competing Interests: The author(s) declare no conflict of interest.

We find that localized rotations of hexagonal clusters of particles occur during rapid dissolution of grain boundary loops in two-dimensional colloidal crystals. These particle vortices, or rotating "granules," are distinct from established models for grain boundary diffusion, which predict that a crystal grain enclosed within another crystal will dissolve at a constant rate. Our measurements of colloidal crystal experiments and Brownian dynamics simulations reveal grain boundary motion that is described by two distinct processes: slow dissolution due to the diffusion of individual particles, and rapid dissolution due to collective granule rotation. In the latter process, hexagonal clusters of particles rotate together in granules whose shape and position are determined by the underlying moiré pattern. Furthermore, these vortices guide cooperative strings of particles that move along the edges of the hexagonal granules. Including this vortex mechanism may improve models for grain coarsening in polycrystalline materials, ultimately offering improved predictions for the time evolution of material properties.

As complete host resistance in soybean has not been achieved, Sclerotinia stem rot (SSR) caused by Sclerotinia sclerotiorum continues to be of major economic concern for farmers. Thus, chemical control remains a prevalent disease management strategy. Pesticide evaluations were conducted in Illinois, Iowa, Michigan, Minnesota, New Jersey, and Wisconsin from 2009 to 2016, for a total of 25 site-years ( n = 2,057 plot-level data points). These studies were used in network meta-analyses to evaluate the impact of 10 popular pesticide active ingredients, and seven common application timings on SSR control and yield benefit, compared with not treating with a pesticide. Boscalid and picoxystrobin frequently offered the best reductions in disease severity and best yield benefit ( P < 0.0001). Pesticide applications (one- or two-spray programs) made during the bloom period provided significant reductions in disease severity index (DIX) ( P < 0.0001) and led to significant yield benefits ( P = 0.0009). Data from these studies were also used in nonlinear regression analyses to determine the effect of DIX on soybean yield. A three-parameter logistic model was found to best describe soybean yield loss (pseudo- R 2 = 0.309). In modern soybean cultivars, yield loss due to SSR does not occur until 20 to 25% DIX, and considerable yield loss (-697 kg ha -1 or -10 bu acre -1 ) is observed at 68% DIX. Further analyses identified several pesticides and programs that resulted in greater than 60% probability for return on investment under high disease levels.

Sudden death syndrome (SDS) of soybean, caused by Fusarium virguliforme, is a significant disease of soybean. The suite of factors that influence disease development is incompletely understood. The goal of this study was to determine the effects of pathogen population levels, crop residues, seed exudates, and their interactions on development of SDS and growth of F. virguliforme. Studies were conducted in a greenhouse with cultivars susceptible and partially resistant to SDS, four pathogen population levels, and six crop residue treatments (none; ground corn seed, stalks, and roots; ground soybean stems; and sorghum seed). Root rot was assessed 15 and 50 days after inoculation (dai) and foliar disease and plant biomass were assessed 50 dai. Population level increases and crop residues had significant interacting effects on increasing foliar disease severity and root rot and on biomass reduction. Disease severity was positively correlated with population and biomass was negatively correlated. Plants grown with no crop residues exhibited low or no root rot or foliar disease 15 dai, and severity was greatest with corn and sorghum seed. In vitro studies were conducted to test the effects of exudates collected from germinating soybean and corn seed on growth of F. virguliforme and F. solani. Growth of these fungi was greater in exudates than in water. More growth occurred in exudates collected during soybean radicle emergence than those sampled at other times during germination. These studies show that pathogen population levels and crop-derived nutrients in soil interact and influence severity of SDS. Results have implications for gaging disease risk and managing SDS.

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.

Multiple fungal species have been associated with root rot of soybean (Glycine max) in the United States, but root rot in Minnesota (MN) also occurs in plants not known to be infected with previously reported pathogens (1). Soybean plants that lacked foliar symptoms, but exhibited taproot and lateral root necrosis were observed in 15 fields from nine counties in MN during 2007 and 2008. Plants were arbitrarily dug up at the R3 growth stage in July as part of a root rot study. Roots were washed, surface disinfested in 0.5% NaOCl for 3 min, rinsed in deionized water, dried, and embedded in potato dextrose agar (PDA). Thirty isolates with morphological characteristics consistent with those of Clonostachys rosea were recovered in total from necrotic lesions on different plants from all fields (3). For further morphological characterization, cultures were grown on PDA for 1 week at 24°C in the dark. Colonies were 39 to 46 mm in diameter, yellowish-white, and the surface was felty to tomentose with thick aerial hyphae. Primary conidiophores were Verticillium-like with two to three levels. The stipe length measured 65 to 105 μm and the base width was 5 μm. Primary conidia were smooth, hyaline, slightly curved, with an average length and width of 7 to 9 × 2.6 to 3 μm. Secondary conidiophores were penicillate with two or three whorls of phialides. The stipe length measured 50 to 75 μm, base width was 5 μm, and penicillus height was 25 to 35 μm. Secondary conidia were 5 to 6 × 2.5 μm. Perithecia were not produced. The identity of isolates was confirmed by sequencing the internal transcribed spacer (ITS) locus using the primers ITS1F/ITS4. BLAST analysis of the sequences in the NCBI database resulted in a 99.8 to 100% match for both C. rosea and its teleomorph Bionectria ochroleuca (e.g., HM751081, GU256766). Each isolate was tested for pathogenicity on soybean by initially growing it on sterile sorghum grain for 2 weeks at 23°C. Sterile sorghum was used for control plants. Seeds of soybean 'AG2107' were planted in 11.4-cm square pots containing pasteurized potting mix and a 25-cm 3 layer of infested or sterile sorghum placed ~1 cm below the seeds. Two replicate pots containing four plants each were used per treatment and the experiment was repeated once. Root rot was assessed 28 days after planting in a greenhouse at 23°C day and 18°C night with a 14-h photoperiod. Twenty-eight of 30 C. rosea isolates caused taproot necrosis on inoculated plants in both experiments, whereas control roots did not exhibit necrosis. Approximately 6% of inoculated plants also developed interveinal chlorosis and marginal necrosis on trifoliates. Isolations were attempted from roots of all plants, and the isolates recovered from inoculated plants were identified as C. rosea based on morphology and ITS sequences. This fungus was not isolated from control plants. C. rosea was also isolated from petioles of symptomatic trifoliates, indicating systemic colonization of the plants. To our knowledge, this is the first report of C. rosea causing root rot of soybean and systemically colonizing soybean. This fungus may have been previously isolated from asymptomatic soybean plants and identified as Gliocladium roseum (2). The impact of this fungus on soybean production is unknown. References: (1) G. Hartman et al. Compendium of Soybean Diseases. 4th ed. The American Phytopathological Society, St. Paul, MN, 1999. (2) J. D. Mueller and J. B. Sinclair. Trans. Brit. Mycol. Soc. 86:677, 1986. (3) H.-J. Schroers et al. Mycologia 91:365, 1999.

Soybean rust caused by Phakopsora pachyrhizi Syd. & P. Syd is a destructive foliar disease of soybean (Glycine max L), which was first confirmed in North America in Louisiana during 2004 (4). Soybean rust (SBR) has also been reported late in the growing season as far north as Illinois, Indiana, and Iowa. SBR was first confirmed in Mexico in 2005 in the state of San Luis Potosi on soybean (3) and subsequently reported in the states of Tamaulipas, Veracruz, and the southwestern coast of Chiapas. Symptoms of SBR were observed on leaves of multiple, nearly mature soybean plants near the city of Campeche (19.72796°N, 90.0771°W) on the Gulf Coast of the Yucatan Peninsula during November 2008. Angular and irregular chlorotic lesions on leaves contained necrotic spots and pale brown, erumpent, cone-like uredinia with a central opening. Ellipsoid to obovoid, echinulate, light tan urediniospores (10 to 13 × 16 to 18 μm) were observed microscopically. DNA was extracted from leaf tissue containing uredinia and from asymptomatic tissue with the DNeasy Plant Mini Kit (Qiagen, Valencia, CA). P. pachyrhizi was confirmed in the symptomatic leaves by a PCR assay with Ppm1/Ppa2 primers, but not from the asymptomatic leaves (1). Subsequently, the DNA extracted from symptomatic and asymptomatic leaf tissues was tested again in another laboratory by a specific quantitative PCR assay (1), and positive results for the presence of soybean rust were obtained only from the symptomatic tissue. As a final confirmatory step, amplified DNA from the PCR assay was sequenced, and the results matched P. pachyrhizi sequences in the GenBank database. To our knowledge, these observations confirm for the first time the presence of P. pachyrhizi in the state of Campeche of southern Mexico. Although it was confirmed on soybean during 2008, it is not known how long the pathogen has been present or which other hosts may be infected there. The presence of SBR on the Yucatan Peninsula is significant because of its potential effects on local plant hosts. In addition, the climate allows possible year-round survival of the pathogen and long-distance transport of urediniospores to the United States. Potential transport of SBR spores from this part of Mexico to the United States has been reported through the application of NOAA's HYSPLIT (Hybrid Single Particle Lagrangian Integrated Transport) model and atmospheric back-trajectory analysis (2). References: (1) R. D. Frederick et al. Phytopathology 92:217, 2002. (2) S. V. Krupa et al. Plant Dis. 90:1254, 2006. (3) A. C. Rodriguez et al. Plant Dis. 90:1260, 2006. (4) R. W. Schneider et al. Plant Dis. 89:774, 2005.

Rapidly growing mycobacteria (RGM) are ubiquitous in the environment but cause lung disease in only a fraction of exposed individuals. This variable susceptibility to disease implies vulnerability to RGM infection due to weakness in host defense. Since most persons who contract RGM lung disease have no known host defense defect, it is likely that uncharacterized host deficiencies exist that predispose to RGM infection. Alpha-1-antitrypsin (AAT) is a host factor that may protect individuals from respiratory infections. Therefore, we assessed AAT protein anomalies as a risk factor for RGM lung disease. In a cohort of 100 patients with RGM lung disease, Mycobacterium (M.) abscessus was the most prevalent organism, isolated in 64 (64%) subjects. Anomalous AAT proteins were present in 27% of the cohort, which is 1.6 times the estimated prevalence of anomalous AAT proteins in the United States population (p=0.008). In in vitro studies, both AAT and a synthetic inhibitor of serine proteases suppressed M. abscessus infection of monocyte-derived macrophages by up to 65% (p<0.01). AAT may be an anti-RGM host-defense factor, and anomalous AAT phenotypes or AAT deficiency may constitute risk factors for pulmonary disease due to RGM.

The Mycotrim Triphasic flask system (Irvine Scientific, Irvine, Calif.) was compared with a system composed of Mycotrim GU broth (Irvine Scientific) and A7 or A8 agar (Remel, Lenexa, Kans.) for the ability to detect Ureaplasma urealyticum and Mycoplasma hominis from 129 genital specimens. Of the 64 specimens positive for U. urealyticum, 25, 98, and 100% were detected on Mycotrim Triphasic agar and A7 and A8 agars, respectively. All 18 specimens that grew M. hominis were detected by A7 and A8 agars, and 94% grew on Mycotrim Triphasic agar. Mycotrim GU broth detected all of the positive specimens, and Mycotrim Triphasic broth detected all but one. Mycotrim GU broth inoculated simultaneously with either A7 or A8 agar was found to be more sensitive and cost-effective than the Mycotrim Triphasic flask system.

von Willebrand factor (vWf) mediates the adherence of platelets to exposed vascular subendothelium. During hematogenous metastasis in certain model systems, platelets are also deposited at endothelial surfaces in heterotypic aggregates with tumor cells. The role of vWf in this metastatic event was investigated by examining the interaction between purified iodine 125-labeled vWf and the human tumor cell lines, U937 and CA46. vWf-tumor cell binding was specific, partially reversible, and saturable at 4 degrees C. At 37 degrees C, however, U937 cell binding sites could not be saturated, suggesting endocytosis as a possible mechanism of interaction. When constant amounts of vWf were added, interactions with tumor cells were complete after 60 minutes, but rapidly dissociated over the next 2 hours. With the addition of specific proteinase inhibitors, vWf remained in stable association with tumor cells throughout a 3-hour time course. Loss of vWf antigen in supernatant samples complemented the 125I-labeled vWf bound directly to tumor cells. However, disproportionately large reductions in vWf functional activity were observed and correlated with alterations in multimeric structure. These data suggest an initial binding of vWf to some tumor cells, followed by a time-dependent loss of structural and functional integrity. VWf may contribute to tumor cell arrest within the microvasculature and may influence other tumor cell-subendothelial interactions as the adhesive function of vWf is subsequently modified.

The ability of von Willebrand factor protein (vWF) to agglutinate platelets with ristocetin depends upon the presence of its highest molecular weight multimers (HMWM) and its intact carbohydrate structure. Previously we demonstrated that the HMWM are preferentially adsorbed to purified fibrillar type I collagen. The role of the carbohydrate structure of vWF in this function has not been established. In these studies complete desialylation (greater than 95%) of the intact protein by neuraminidase did not interfere with the normal adsorption of vWF activity to type I collagen. In contrast, modification of the penultimate galactose of the desialylated protein with galactose oxidase or beta-galactosidase markedly reduced adsorption of vWF activity by collagen. Subsequent reduction of the oxidized desialylated protein with potassium borohydride completely regenerated the normal adsorption of vWF activity by collagen. Enzymatic modification of the penultimate galactose moiety of vWF resulted in a loss of the HMWM, as observed following SDS-glyoxyl agarose electrophoresis. This was in contrast to desialylated vWF, which appeared intact structurally and which predictably lost its HMWM upon exposure to collagen in a manner similar to native vWF. Therefore, the carbohydrate structure of vWF and, in particular, the penultimate galactose moiety, may be critical for vWF-collagen interactions and for the mediation of primary hemostasis.

The influence of protein depletion on serum factors in PHA lymphocyte blastogenesis was studied in a rat model. Buffalo rats were divided randomly into two groups and fed either a protein-free (PF) diet or a regular 25% protein diet (RD). At weekly intervals, lymph node lymphocytes were cultured with PHA in either autologous or pooled 10% rat serum. For weeks 2 through 6, PHA stimulated blastogenesis of lymphocytes from rats maintained on PF diet incubated with autologous serum decreased significantly compared with RD lymphocytes cultured with RD serum. At week 4, PHA blastogenesis of PF lymphocytes cultured with RD serum was similar to that of RD lymphocytes incubated with RD serum. AT weeks 5 and 6, PHA stimulation of PF lymphocytes assayed with RD serum was depressed compared with RD lymphocytes cultured with RD. For weeks 4 through 6, blastogenesis of RD lymphocytes assayed with PF serum decreased significantly compared with RD lymphocytes incubated with RD serum. Three weeks of protein repletion of rats previously on a PF diet for 6 weeks restored PHA blastogenesis to that observed for lymphocytes from animals in the RD group. The data suggested that suppression of PHA blastogenesis of lymphocytes from rats maintained on PF diet involved a serum factor in the early stages of protein depletion and an additional defect (not serum related) in lymphocyte blastogenesis after prolonged protein depletion. In addition, this defect was corrected after a period repletion.

Sera from 290 hospital patients were tested to compare the sensitivity, specificity, and reproducibility of the hemagglutination treponemal test for syphilis (HATTS) with the fluorescent treponemal antibody absorption test (FTA-ABS). Complete agreement was obtained between the methods when 142 syphilitic sera from patients with various stages of syphilis were tested. By using clinical histories, the specificity with 148 nonsyphilitic sera was determined to be 100% for the HATTS and 96.6% (143 of 148) for the FTA-ABS. Satisfactory reproducibility was obtained with both methods. Compared with the FTA-ABS, the HATTS was more specific, easier, and more economical to perform. We therefore recommend the HATTS as a suitable alternative to the FTA-ABS.