Identifying highly connected counties compensates for resource limitations when evaluating national spread of an invasive pathogen

Surveying invasive species can be highly resource intensive, yet near-real-time evaluations of invasion progress are important resources for management planning. In the case of the soybean rust invasion of the United States, a linked monitoring, prediction, and communication network saved U.S. soybean growers approximately $200 M/yr. Modeling of future movement of the pathogen (Phakopsora pachyrhizi) was based on data about current disease locations from an extensive network of sentinel plots. We developed a dynamic network model for U.S. soybean rust epidemics, with counties as nodes and link weights a function of host hectarage and wind speed and direction. We used the network model to compare four strategies for selecting an optimal subset of sentinel plots, listed here in order of increasing performance: random selection, zonal selection (based on more heavily weighting regions nearer the south, where the pathogen overwinters), frequency-based selection (based on how frequently the county had been infected in the past), and frequency-based selection weighted by the node strength of the sentinel plot in the network model. When dynamic network properties such as node strength are characterized for invasive species, this information can be used to reduce the resources necessary to survey and predict invasion progress.     

The impact of invasive fungi on agricultural ecosystems in the United States

Invasive fungi and other non-indigenous plant pathogens have had a significant effect on American agriculture for hundreds of years. At present crop loss due to invasive plant pathogens, especially fungi, is estimated at $21 billion per year in the United States, greater than the loss caused by non-indigenous insects. Plant pathogenic fungi are difficult to detect and identify. Thus knowledge of which fungi pose a threat is essential to prevent their entry by means others than inspection. In this paper, examples are presented of invasive fungi on agricultural commodities introduced into the United States. In all cases two factors have been crucial: first, the pathway through which these fungi have entered, and second, systematic knowledge to prevent and respond to the new invasive species. Historically important plant pathogens such as black stem rust of wheat still cause considerable damage while others such as late blight of potato appear to be having a resurgence. Known previously in Australia, then moving to Africa and South America, the virulent species of soybean rust appeared in the U.S. in 2004 but has not been as devastating as anticipated. Plant pathogenic fungi on specialty crops such as daylily, gladiola and chrysanthemum are threatened by rust fungi recently found in the U.S. apparently brought in on infected germplasm. A crisis in the export of U.S. wheat occurred in the late 1990’s when the molecular diagnostic test for Karnal bunt gave a false positive response to a closely related but previously unknown species. Many potentially dangerous plant pathogens of crop plants have not yet been introduced into the U.S. It is critical that meticulous surveillance be conducted as plant material enters the country as well as where crops are grown prior to shipment. In addition, the scientific infrastructure is needed to be able to respond quickly to new invasive fungi. This requires sound systematic knowledge of plant pathogenic fungi both in the U.S. and around the world and a cadre of systematic experts who can characterize invasive fungi.     

Initial epidemic area is strongly associated with the yearly extent of soybean rust spread in North America

Hosts of soybean rust (Phakopsora pachyrhizi) are sensitive to low temperatures, limiting this obligate parasite in the United States to overwintering sites in a restricted area along the Gulf Coast. This temperature sensitivity of soybean rust hosts allowed us to study spatial spread of epidemic invasions over similar territory for seven sequential years, 2005–2011. The epidemic front expanded slowly from early April through July, with the majority of expansion occurring from August through November. There was a 7.4-fold range of final epidemic extent (0.4–3.0 million km²) from the year of smallest final disease extent (2011) to that of the largest (2007). The final epidemic area of each year was regressed against epidemic areas recorded at one-week intervals to determine the association of final epidemic extent with current epidemic extent. Coefficients of determination for these regressions varied between 0.44 and 0.62 during April and May. The correlation coefficients varied between 0.70 and 0.96 from early June through October, and then increased monotonically to 1.0 by year’s end. Thus, the spatial extent of disease when the epidemics began rapid expansion may have been a crucial contributor to subsequent spread of soybean rust. Our analyses used presence/absence data at the county level to evaluate the spread of the epidemic front only; the subsequent local intensification of disease could be strongly influenced by other factors, including weather.     

Estimates of Disease Effects on Soybean Yields in the United States 2003 to 2005

Research must focus on management of diseases that cause extensive losses, especially when funds for research are limited. Knowledge of the losses caused by various soybean diseases is essential when prioritizing research budgets. The objective of this project was to compile estimates of soybean yields suppressed due to diseases for each soybean-producing state in the US from 2003 to 2005. The goal was to provide this information to help funding agencies and scientists prioritize research objectives and budgets. Yield suppression due to individual diseases varied among regions in the US, and the total of soybean yields suppressed due to diseases in the US varied among years. Soybean cyst nematode suppressed US soybean yield more during 2003 to 2005 than any other disease. Phytophthora root and stem rot, sudden death syndrome, and seedling diseases ranked in the top four on the list of diseases that suppressed soybean yield during these years. This is the first report of soybean yield suppression due to Asian soybean rust in the United States.     

Predicting the risk of soybean rust in Minnesota based on an integrated atmospheric model

To minimize crop loss by assisting in timely disease management and reducing fungicide use, an integrated atmospheric model was developed and tested for predicting the risk of occurrence of soybean rust in Minnesota. The model includes a long-range atmospheric spore transport and deposition module coupled to a leaf wetness module. The latter is required for spore germination and infection. Predictions are made on a daily basis for up to 7 days in advance using forecast data from the United States National Weather Service. Complementing the transport and leaf wetness modules, bulk (wet plus dry) atmospheric deposition samples from Minnesota were examined for soybean rust spores using a specific DNA test and sequence analysis. Overall, the risk prediction worked satisfactorily within the bounds of the uncertainty associated with the use of modeled 7-day weather forecasts, with more than 65% agreement between the model forecast and the DNA test results. The daily predictions are available as an advisory to the user community through the University of Minnesota Extension. However, users must take the actual decision to implement the disease management strategy.     

Identification of Pathotypes in the Daylily Rust Pathogen Puccinia hemerocallidis

Daylily rust, caused by Puccinia hemerocallidis, has been present in the United States since 2000. In 2003, inoculations with a single isolate of P. hemerocallidis identified daylily cultivars with high levels of resistance to the fungus. The present study was carried out to determine if pathotypes of P. hemerocallidis are present in the south eastern United States. Sixteen isolates of P. hemerocallidis were each inoculated onto leaf segments from 19 daylily cultivars and the resulting disease phenotype assessed. A significant effect of rust isolate on host reaction phenotype was observed for nine of the 19 daylily cultivars. Five of the nine cultivars displayed reaction phenotypes with different isolates of P. hemerocallidis that included at least one susceptible or moderately susceptible and also resistant phenotypes. These results indicate that different pathotypes of the fungus are present in the south east United States. Daylily hybridizers interested in screening for host resistance to P. hemerocallidis will need to include multiple isolates of the fungus to allow for this host specialization.     

Ethanol fermentation and potential.

Ethyl alcohol is one of the United States and world's major chemicals. Beverage alcohol in the United States must be prepared from cereal grains or other natural products. The U.S. industrial alcohol market has remained relatively stable for several years at approximately 300 million gallons annually. Most of this has been produced synthetically from petroleum raw material (gas and oil). These raw materials are experiencing major price increases and are in short supply. The production of ethyl alcohol from cereal grains and cellulosic raw materials by fermentation is technically feasible and has been proven. Alcohol produced from all such materials is equal to synthetic alcohol in quality and performance. Competitive economics have controlled the basic raw materials used. The major potential new ethyl alcohol market is as a component of automobile fuels. A 10% alcohol-gasoline blend in the United States would annually require over 10 billion gallons of anhydrous alcohol. Use of alcohol for this purpose is technically feasible. However, alcohol has not been economically competitive to date.     

Evaluating a science-based decision support tool used to prioritize brook charr conservation project proposals in the eastern United States

Declines in brook charr (Salvelinus fontinalis) throughout its historic eastern United States of America (U.S.) range prompted the formation of the Eastern Brook Trout [Charr] Joint Venture (Joint Venture) whose mandate is to restore these charr by working cooperatively at a range-wide, regional-scale. Joint Venture habitat projects in the U.S. are initiated by local community-based organizations, assisted by fisheries management institutions, and funded through the U.S. Fish and Wildlife Service. In order to assist with ranking these community-based proposals for available funding, the Joint Venture designed a quantitative scoring method as a decision support tool that addressed range-wide threats that were documented to limit brook charr production. These threats include habitat modification (e.g., dams, urbanization, and agricultural landuse) and interactions with antagonistic non-native species [i.e., brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss)]. This article evaluated the prioritization method used by comparing the quantitative rankings of the proposals with the final reports for 12 completed projects using paired t tests for unequal sample sizes and variance. Two of the 12 comparisons revealed statistically significant differences (P < 0.05) between project proposals and final reports; namely, the scoring criteria for the proposals did not accurately reflect the outcome of these projects in relation to brook charr management. Large inter-quartile ranges between reviewer scores were common, indicating that the quantitative scoring method includes qualitative elements. In addition to the science-based criteria, subjective value judgments by individual reviewers have factored into the Joint Venture’s decision making process. By evaluating the decision support tool, this analysis aims to assist the Joint Venture in structuring its approach to conservation and rehabilitation of brook charr populations in the eastern U.S. To better improve the Joint Venture’s ability to address brook charr management on a regional level, we recommend that future proposal prioritization scoring criteria provide more explicit guidance for accurate scoring, separate scoring methods for policy and assessment work, and a weighting factor for larger than sub-watershed projects and for scoring criteria for which information is unknown.     

Dorsett-morse soybean collection trip to East Asia: 50 year retrospective

This paper is devoted to the analysis of the 4,451 soybean (Glycine max,) accessions collected by P. H. Dorsett and W. J. Morse during their plant exploration trip to east Asia 1929–1931. Until about 1950 the collection was used primarily for the development of vegetable type soybean cultivars. During this period many of the accessions were lost. Today only 945 of the original 4,451 accessions are available in the United States soybean germplasm collection. From the 1950s to the 1980s, as soybean production increased in the United States, so did plant pathogen problems. The Dorsett-Morse soybean accessions have been extremely valuable to plant pathologists and breeders as sources of resistance to certain pathogens. Individual genotypes in the collection have been used for genetic studies on morphological, physiological and biochemical traits. Due to the development and distribution of higher-yielding soybean cultivars, farmers in east Asia are no longer growing lower-yielding landraces. Although these landraces are now extinct in east Asia, many were collected by Dorsett and Morse and are preserved in the United States soybean collection. Over the years, the Dorsett-Morse collection has increased in value and will be as useful to soybean scientists in the future as it has been in its first 50 yr of existence.     

Independent emergence of Yersinia ruckeri biotype 2 in the United States and Europe

Biotype 2 (BT2) variants of the bacterium Yersinia ruckeri are an increasing disease problem in U.S. and European aquaculture and have been characterized as serovar 1 isolates that lack both peritrichous flagella and secreted phospholipase activity. The emergence of this biotype has been associated with an increased frequency of enteric redmouth disease (ERM) outbreaks in previously vaccinated salmonid fish. In this study, four independent specific natural mutations that cause the loss of both motility and secreted lipase activity were identified in BT2 strains from the United States, United Kingdom, and mainland Europe. Each of these was a unique mutation in either fliR, flhA, or flhB, all of which are genes predicted to encode essential components of the flagellar secretion apparatus. Our results demonstrate the existence of independent mutations leading to the BT2 phenotype; thus, this phenotype has emerged separately at least four times. In addition, BT2 strains from the United Kingdom were shown to have the same mutant allele found in U.S. BT2 strains, suggesting a common origin of this BT2 lineage. This differentiation of distinct BT2 lineages is of critical importance for the development and validation of alternative vaccines or other treatment strategies intended for the control of BT2 strains.     

Colicin Typing as an Epidemiological Tool in the Investigation of Outbreaks of Shigella sonnei

Shigella sonnei has become the most frequently reported cause of shigellosis in the United States. Since Shigella subgroup D has no other serotypes, colicin production has been used as a basis for differentiating and identifying epidemiologically related strains. The results of colicin typing 115 cultures of S. sonnei from eight outbreaks of shigellosis occurring in widely separated regions of the United States support the usefulness of this technique. In each outbreak, the cultures were either of the same colicin type or were uniformly untypable. Unrelated cases yielded a variety of types. Definitions of the relative frequencies and geographic distributions of the various strains of S. sonnei in the United States await an accumulation of experience with the method.     

Canadian government financial intervention in a marine fishery: The case of newfoundland, 1972/73–1980/81

Abstract

Trade in fish products between Canada and the United States has been the subject of extensive legal activity in the latter country. United States fishing interests have repeatedly attempted to utilize provisions in U.S. law and in the General Agreement on Tariffs and Trade (GATT) to have countervailing duties imposed on imports of Canadian fish products, the prices of which are alleged to be artificially depressed by Canadian government financial support of the industry.

This paper summarizes the state of U.S. and international law on countervailing duties, and surveys recent legal activity on the matter. It then presents hitherto uncollected evidence on government financial support of a major Canadian fishery, the Newfoundland groundfishery. It is found that the total value of expenditures was equal to 31 percent of the value of total fish products in 1980/81. However, subsidies as defined by the U.S. International Trade Administration, in accordance with U.S. law and the GATT, amounted to only 4.5 percent of the value of total fish products in that year.     

Chronomodulated chemotherapy: clinical value and possibilities for dissemination in the United States

Modern medicine has been relatively slow to apply chronotherapeutic principles to standard oncologic practice. Despite the impressive body of evidence supporting the use of chronochemotherapy, with only a rare exception most oncology clinics in the United States lack the expertise and capability to implement it. At the same time, American medicine has increasingly come to recognize the importance of toxicity mitigation, cytoprotection, and quality of life for patients undergoing cancer treatment. However, toxicity mitigation strategies such as chronomodulated infusional chemotherapy and novel cytoprotective agents are not widely embraced by U.S. physicians. This article explores some reasons why this situation exists, including the influence of non-medical biases that may affect management decisions on the application of chemotherapy. The author conducted a survey of U.S. companies representing the three private insurance payers available (HMO, PPO, Indemnity) as well as representatives of Medicare and Medicaid. Responses to the survey confirmed that U.S. insurers do not at present officially reimburse for chronotherapy; however, changes will come about through educational efforts aimed at increasing awareness among insurers as to the clinical benefits and cost-effectiveness of this mode of treatment. At this juncture, the outlook for cancer chronotherapy as a first-line approach to the treatment of metastatic cancer in the United States remains uncertain. Under the current method of insurance reimbursement, the advancement of chronotherapy in the United States is threatened despite evidence that such treatment is both therapeutically sound and cost-effective.     

Phomopsis (Diaporthe) Species as the Cause of Soybean Seed Decay in Korea

Soybeans are an important crop known to harbour a complex of Diaporthe and Phomopsis species. This complex has been reported to be involved in several soybean diseases, including Phomopsis seed decay. In this study, two species of Diaporthe/Phomopsis fungi from soybean plants were identified by morphological and molecular characterizations. Koch's postulates were confirmed by pathogenicity tests on hypocotyls of soybean seedlings. Phomopsis longicolla was found to be the most common and virulent pathogen to soybeans in Korea. Phomopsis sp., which was considered as a new soybean pathogen, might have been introduced from other plants given that similar strains of Phomopsis sp. have infected fruit trees in China, Japan and Portugal and vegetable plants in the United States.     

Interspecies gene transfer provides soybean resistance to a fungal pathogen

Fungal pathogens pose a major challenge to global crop production. Crop varieties that resist disease present the best defence and offer an alternative to chemical fungicides. Exploiting durable nonhost resistance (NHR) for crop protection often requires identification and transfer of NHR‐linked genes to the target crop. Here, we identify genes associated with NHR of Arabidopsis thaliana to Phakopsora pachyrhizi, the causative agent of the devastating fungal disease called Asian soybean rust. We transfer selected Arabidopsis NHR‐linked genes to the soybean host and discover enhanced resistance to rust disease in some transgenic soybean lines in the greenhouse. Interspecies NHR gene transfer thus presents a promising strategy for genetically engineered control of crop diseases.     

Non-target impacts of soybean rust fungicides on the fungal entomopathogens of soybean aphid

Soybean aphid, Aphis glycines, has caused serious economic damage to soybean across the North Central US since its introduction to North America in 2000. The management of another invasive soybean pest, Asian soybean rust, Phakopsora pachyrhizi, using foliar fungicide applications has the potential to impact soybean aphid populations by suppressing beneficial fungal entomopathogens. In 2005 and 2006, we applied recommended soybean rust fungicide treatments, consisting of strobilurin and triazole fungicides, to small soybean plots in two locations to assess if such applications might suppress aphid fungal epizootics. In Lamberton, MN, in 2005, during the epizootic, fungicide-treated plots averaged 2.0 ± 0.7% (mean ± SE) disease prevalence while untreated plots averaged 14.2 ± 5.6%. In 2007, we applied strobilurin and strobilurin-triazole mix fungicides to single-plant microplots either before or after release of Pandora neoaphidis, the most commonly observed aphid pathogen in 2005 and 2006. Treatments that contained a mixture of two active ingredients significantly lowered peak and cumulative aphid disease prevalence in both early and late reproductive stage soybeans indicating that fungicide mixtures used to manage soybean rust can negatively impact an aphid-specific fungal pathogen. However, no consistent soybean aphid population response was observed in these studies of low levels of aphid fungal infection.     

Streptococcal Superantigen,Mitogenic Factor,and Pyrogenic Exotoxin B Expressed by Streptococcus pyogenes

Abstract

Streptococcus pyogenes is a Gram-positive human bacterial pathogen that causes pharyngitis, tonsillitis, skin infections (impetigo, erysipelis, and other forms of pyoderma), acute rheumatic fever (ARF), scarlet fever (SF), poststreptococcal glomerulonephritis (PSGN), a streptococcal toxic shock syndrome (STSS), and necrotizing fasciitis. These infections are some of the most economically and medically important conditions that affect humans. For example, globally, ARF is the most common cause of pediatric heart disease. It is estimated that in India more than six million school-aged children suffer from rheumatic heart disease (1). In the United States, “sore throat” is the third most common reason for physician office visits and S. pyogenes is recovered from about 30% of children with this complaint (2). It has been estimated that there are 25–35 million cases of streptococcal pharyngitis per year in the United States, and these infections cause 1–2 billion dollars per year in direct health care costs (3,4). Although the continued great morbidity and mortality caused by S. pyogenes in developing nations, the significant health care financial burden attributable to group A streptococci in the United States, and increasing levels of antibiotic resistance (5), have highlighted the need for a fuller understanding of the molecular pathogenesis of streptococcal infection, it has been the relatively recent intercontinental increase in streptococcal disease frequency and severity (6,7) that has resulted in renewed interest in S. pyogenes virulence factors and host-parasite interactions.     

Two Erysiphe species associated with recent outbreak of soybean powdery mildew: results of molecular phylogenetic analysis based on nuclear rDNA sequences

 Serious outbreaks of powdery mildew by a fungus belonging to the mitosporic genus Oidium subgenus Pseudoidium have been reported on soybean (Glycine max) in a wide area of eastern Asia since 1998. The taxonomic and phylogenetic placement of the causal fungus has not yet been determined because of lack of the perfect stage. We found ascomata having mycelioid appendages on a single leaf of soybean infested by powdery mildew. Molecular phylogenetic analysis was conducted based on a total of 14 sequences of the rDNA internal transcribed spacer (ITS) region from 13 soybean and wild soybean (Glycine soja) materials collected in Japan, Korea, Vietnam, and the United States, combined with 47 sequence data obtained from the DNA databases. It was revealed that two Erysiphe species were associated with the outbreak of soybean powdery mildew. There was 16% difference between the two species in genetic divergence of the ITS sequence. One species with perfect stage has an ITS sequence identical to that of Erysiphe glycines on Amphicarpaea and is identified as Erysiphe glycines based on the ITS sequence and morphology of ascomata. The second species, without the perfect stage, is likely to be Erysiphe diffusa (= Microsphaera diffusa), known as the fungus causing soybean powdery mildew in the United States, because the ITS sequences are identical to those from materials collected in the United States. However, we need materials having ascomata of E. diffusa to confirm the species name. Received: March 15, 2002 / Accepted: May 22, 2002     

Circulating IgG antibodies against fungal and actinomycete antigens in the sera of farmer's lung patients from different countries

Sixty-nine farmer's lung patients and 28 normal controls from four countries (Finland, Switzerland, Canada and the United States) were investigated for antibody levels against 13 antigens commonly used for the screening panel for hypersensitivity pneumonitis. Of these antigens, eight were from the Medical College of Wisconsin (United States) and five were from the University of Kuopio (Finland). IgG antibodies against these antigens were studied in 97 sera using a sensitive biotin-avidin-linked enzyme immunoassay. The results indicate that the mean antibody titer against Micropolyspora faeni was highest in the United States (U.S.) followed by Finland. Both Finnish and U.S. antigens reacted almost identically against various groups of patients, although the degree of reactivity varied considerably. Higher antibody levels against Thermoactinomyces vulgaris were detected in Finnish patients than patients from other countries while patients from all four countries showed elevated levels of antibodies against T. candidus. This study demonstrates that antigens from identical species, irrespective of geographic origin, reacted similarly. However, variability between antigens of the same species was still considerably significant. Since the microbiological flora of moldy hay varies widely in different regions, the microbial species associated with the disease at a given geographical area has to be determined before selecting antigens for serological studies. The antigens currently used in various laboratories are crude preparations and need to be purified and standardized for dependable results. Until such antigens are available, all antigenic preparations used in the immunological evaluation of patients should be immunochemically characterized for their reproducibility and reliability although the ultimate goal should be to obtain standardized pure antigens for dependable immunodiagnosis of farmer's lung.     

U.S. Federal Initiatives to Support Biomass Research and Development

This article provides a brief overview of federal initiatives in the United States to support biomass research, demonstration, and development. The interest in the biomass industry and U.S. federal efforts to spur development of, increased production of, and use of biopower, biofuels, and biobased products, collectively known as the "biomass industry", are discussed. A growing level of leadership from the executive branch of the federal government and support by the U.S. Congress are documented. Five important policy drivers that support this heightened emphasis on biomass for power, fuels, and products are identified and discussed. The current status of U.S. dependence on these renewable energy sources is briefly outlined. Federal biomass funding activity for the current fiscal year by the U.S. Department of Agriculture and the U.S. Department of Energy, two major federal participants in research, demonstration, and development for this industry, is briefly outlined. This funding commitment is placed into an overall context of total federal support for all research and development. Finally, the article suggests future market penetration targets for this industry, emphasizes the importance of infrastructure development necessary to support the industry's growth, and notes the payoff from such development for farmers, foresters, rural communities, and the environment.