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PubMed | University of Rome La Sapienza, BBCA onlus, USDA ARS and ENEA
Type: Journal Article | Journal: Bulletin of entomological research | Year: 2016

Trichosirocalus horridus sensu lato has been used as a biological control agent of several invasive thistles (Carduus spp., Cirsium spp. and Onopordum spp.) since 1974. It has been recognized as a single species until 2002, when it was split into three species based on morphological characters: T. horridus, Trichosirocalus briesei and Trichosirocalus mortadelo, each purported to have different host plants. Because of this taxonomic change, uncertainty exists as to which species were released in various countries; furthermore, there appears to be some exceptions to the purported host plants of some of these species. To resolve these questions, we conducted an integrative taxonomic study of the T. horridus species complex using molecular genetic and morphological analyses of specimens from three continents. Both mitochondrial cytochrome c oxidase subunit I and nuclear elongation factor 1 markers clearly indicate that there are only two distinct species, T. horridus and T. briesei. Molecular evidence, morphological analysis and host plant associations support the synonymy of T. horridus (Panzer, 1801) and T. mortadelo Alonso-Zarazaga & Snchez-Ruiz, 2002. We determine that T. horridus has been established in Canada, USA, New Zealand and Australia and that T. briesei is established in Australia. The former species was collected from Carduus, Cirsium and Onopordum spp. in the field, whereas the latter appears to be specific to Onopordum.

Brennan E.B.,USDA ARS | Boyd N.S.,Dalhousie University | Smith R.F.,University of California Cooperative Extension | Foster P.,Phil Foster Ranches
Agronomy Journal | Year: 2011

Rye (Secale cereale L.) is an important cover crop in high-value vegetable production in California. A 2-yr winter study on organic farms in Salinas and Hollister, CA evaluated cover crop population densities, ground cover, aboveground dry matter (DM), and N content of rye and five legume-rye mixtures. Mixtures had 60 or 90% legumes by seed weight and included twoor more of the following legumes: faba bean (Vicia faba L.), vetches (V. benghalensis L., V. dasycarpa Ten., V. sativa L.), and pea (Pisum sativum L.). Seeding rates were 90 (rye) and 140 (mixtures) kg ha-1, and densities were 142 to441 plants m-2. Early-season ground cover was usually greater in monoculture rye and the 60% legume mixtures than the 90% legume mixtures. Total DM, and legume and rye DM in mixtures diff ered by year, site, harvest, and cover crop. Total DM was usually at least twotimes higher at season end than mid-season. Th e 90% legume mixtures generally produced more legume DM than the 60% legume mixtures, but legume DM usually declined aft er mid-season. Rye DM increased with rye density. Total cover crop N uptake was greater in Hollister than Salinas; however, legume DM and legume N uptake were greater in Salinas. Interactions between site, year, cover crop, and harvest illustrate the complex growth dynamics of legume-rye mixtures. Th e 90% legume mixtures appear most suitable for vegetable production in California because they had a better balance of legume and rye DM at season end. © 2011 by the American Society of Agronomy.

Johnson III W.C.,USDA ARS | Davis J.W.,University of Georgia
HortTechnology | Year: 2014

Timely cultivation with a tine weeder and hand weeding are the primary tools for successful weed control in organic sweet onion (Allium cepa), but conditions frequently arise that delay the initial cultivation. Weeds that emerge during the delay are not effectively controlled by cultivation and herbicides derived from natural products may have a role to control the emerged weeds. It has been reported that clove oil herbicide was more effective when sprayers were calibrated for higher output (>50 gal/acre) compared with sprayers calibrated at ≈25 gal/acre. However, when clove oil was applied at the recommended rate of 10% by volume, herbicide cost was doubled when sprayer output volume was doubled. It was theorized that herbicide adjuvants might improve clove oil efficacy and reduce weed control cost by not needing to increase sprayer output volume. Trials were conducted from 2010 to 2012 to evaluate all possible combinations of two sprayer output volumes and five herbicide adjuvants used with clove oil (10% by volume) for cool season weed control. Sprayer output volumes evaluated were 25 and 50 gal/acre, using spray tips of differing orifice size. Adjuvants evaluated were a material composed of saponins, citric acid plus garlic extract, an emulsified petroleum oil (EPO) insecticide, a conventional petroleum oil adjuvant (POA), no adjuvant used with clove oil, and a nontreated control. Weed control was not consistently improved by applying clove oil (10% by volume) with a sprayer calibrated at 50 gal/acre compared with sprayer calibrated at 25 gal/acre. Improvements in weed control that were occasionally seen did not affect onion yield. Adjuvants provided minimal improvement in weed control from clove oil and did not consistently improve onion yield. Based on these results, clove oil does not provide suitable levels of weed control in organic Vidalia® sweet onion production to justify the expense.

Fritz B.K.,U.S. Department of Agriculture | Hoffmann W.C.,U.S. Department of Agriculture | Bagley W.E.,Wilbur Ellis | Kruger G.R.,University of Nebraska - Lincoln | And 2 more authors.
Atomization and Sprays | Year: 2014

With a number of new spray testing laboratories going into operation and each gearing up to measure spray atomization from agricultural spray nozzles using laser diffraction, establishing and following a set of scientific standard procedures is crucial to long-term data generation and standardization across the industry. It has long been recognized that while offering ease of use as compared to other methods, laser diffraction measurements do not account for measurement bias effects due to differ-ential velocities between differing sized spray droplets, and in many cases significantly overestimate the fine droplet portion of the spray. Droplet sizes and velocities were measured for three agricul-tural flat fan nozzles (8002, 8008, and 6510) each at three spray pressures (138, 276, and 414 kPa) at four downstream distances (15.2, 30.5, 45.7, and 76.2 cm) across a range of concurrent air velocities (0.7-80.5 m/s). At air velocities below 6.7 m/s, large gradients in droplet velocities resulted in over-estimation of both the 10% volume diameter (Dv0:1) by more than 10% and the percent volume of the spray less than 100 m (V<100) was overestimated two-to three-fold. The optimal measurement dis-tance to reduce droplet measurement bias to less than 5% was found to be 30.5 cm with a concurrent air velocity of 6.7 m/s for measuring droplet size from ground nozzles. For aerial spray nozzles, the optimal distance was 45.7 cm. Use of these methods provides for more accurate droplet size data for use in efficacy testing and drift assessments, and significantly increases inter-lab reproducibility. © 2014 by Begell House, Inc.

Chaudhury M.F.,U.S. Department of Agriculture | Sagel A.,USDA ARS | Skoda S.R.,U.S. Department of Agriculture
Journal of Medical Entomology | Year: 2012

The waste artificial larval rearing media of New World screwworms, Cochliomyia hominivorax (Coquerel) were evaluated to determine their effectiveness as oviposition attractants. Various concentrations of waste larval media resulting from rearing screwworm larvae in gel and cellulose fiber-based artificial diets tested over a 4-wk period attracted varying number of gravid screwworm flies to oviposit. Three-day-old waste medium with concentrations of 10 and 25% were most attractive to gravid female flies for oviposition and resulted in the most oviposition. One and 7-d-old wastes at all concentrations were less attractive for oviposition than the 3d-old media. The fresh (0-d-old), 14-d- and 28-d-old waste media were the least attractive substrates for oviposition. The waste from the cellulose fiber-based diet resulted in significantly more oviposition compared with waste from the gel-based diet. Microorganisms growing in the waste media probably produce metabolites that attract gravid screwworm flies to oviposit. Use of the waste products of appropriate age and dilution as oviposition substrates would enhance oviposition in mass production colony cages. © 2012 Entomological Society of America.

Hart J.P.,USDA ARS | Griffiths P.D.,Cornell University
Plant Genome | Year: 2015

Since its emergence in 2001, an aphid-transmitted virus disease complex has caused substantial economic losses to snap bean (Phaseolus vulgaris L.) production and processing in the Great Lakes Region of the United States. The general ineffectiveness of chemical control measures for nonpersistently transmitted viruses established an urgent need for the development and deployment of cultivars with resistance to the component viruses. Our objectives were to further characterize the inheritance of resistance to Bean yellow mosaic virus (BYMV), which is conditioned by the By-2 allele, to adapt genotyping-by-sequencing (GBS) to common bean to discover and genotype genome-wide single nucleotide polymorphisms (SNPs) in a set of recombinant inbred lines (RILs) derived from an introgression program, and to enable and validate marker-assisted selection for By-2. We optimized ApeKI for GBS in common bean and retained 7530 high-quality SNPs that segregated in our introgression RILs. A case–control genomewide association study (GWAS) was used to discover 44 GBS SNPs that were strongly associated with the resistance phenotype and which delimited a 974 kb physical interval on the distal portion of chromosome 2. Seven of these SNPs were converted to single-marker Kompetitive Allele-Specific Polymerase chain reaction (KASP) assays and were demonstrated to be tightly linked to BYMV resistance in an F2 population of 185 individuals. This research enables marker-assisted selection of By-2, provides enhanced resolution for fine mapping, and demonstrates the potential of GBS as a highly efficient, high-throughput genotyping platform for common bean breeding and genetics. © Crop Science Society of America.

Warkentin T.D.,University of Saskatchewan | Delgerjav O.,University of Saskatchewan | Arganosa G.,University of Saskatchewan | Rehman A.U.,University of Saskatchewan | And 4 more authors.
Crop Science | Year: 2012

The majority of the total phosphorus in seeds is stored in the form of phytate, a mixed-cation salt of phytic acid. Phytate is not well digested by humans and monogastric animals. Phosphorus excretion is one of the major pollutants of surface waters in many locations in the world. Important micronutrients such as iron and zinc bound to phytate are also excreted, potentially leading to micronutrient deficiencies. Low-phytate mutants have been developed in several crop species as one strategy to deal with the phytate problem. The objective of this research was the development of low-phytate pea (Pisum sativum L.) using chemical mutagenesis of cultivar CDC Bronco, and the agronomic characterization of two resulting lines. In these lines, phytate phosphorus concentration was reduced by approximately 60%, with a compensating increase in inorganic phosphorus. The low-phytate lines were similar in agronomic performance to CDC Bronco, except for somewhat slower time to flowering and maturity, slightly lower seed weight, and slightly lower grain yield. Low-phytate field pea should have potential to improve phosphorus and micronutrient bioavailability in human and animal diets. © Crop Science Society of America.

This week, we chat about cleaning blueberries with purple plasma, how Tibetan dogs adapted to high-altitude living, and who’s checking ocelot message boards with Online News Editor David Grimm. Plus, Science’s Alexa Billow talks to Joe Paton about how we know time flies when mice are having fun.   Listen to previous podcasts.   [Image: Joseph Sites/USDA ARS; Music: Jeffrey Cook]

News Article | March 15, 2016

Plants grown in high-density or crowded populations often put more energy into growth and maintenance than reproduction. For example, flowering may be delayed as plants allocate resources to growing taller and escape competition for light. This sensitivity to crowding stress has been observed in some varieties of sweet corn, but other varieties show higher tolerance, producing high yields even in crowded conditions. A recent University of Illinois and USDA Agricultural Research Service study attempted to uncover the genetic mechanisms of crowding tolerance in sweet corn. "We were trying to find genes that differentiate sweet corn hybrids that have potential to produce higher yields under crowding stress versus hybrids with lower yields under the same growing conditions," explains U of I crop science researcher Eunsoo Choe. Choe and her team measured observable or phenotypic traits for high- and low-yielding hybrids under crowding stress; these included traits known to correlate with crowding stress, such as plant height, leaf area, and time to maturity. Other traits, such as yield, kernel mass, kernel moisture, and fill percentage were also measured. Lastly, the team extracted genetic material from the plants to explore correlations between gene expression patterns and measured traits. "We found clusters of genes that were related to yield under crowding stress," says Choe. Although gene expression patterns indicated each hybrid utilized unique mechanisms for tolerating crowding stress, the researchers did confirm a common genetic basis for the yield response in the six hybrids tested. Low-yielding hybrids had gene activities related to various stress responses while high-yielding hybrids utilized gene activities more directly related to carbohydrate accumulation. Choe says that genes involved with cell growth were prevalent in low-yielding hybrids; these genes may be responsible for delayed flowering under crowding stress. Conversely, genes associated with carbohydrate metabolism were prevalent in high-yielding hybrids; these genes may relate to maintaining yield under crowding stress. "The gene clusters we identified were very broad in their biological functions," notes Choe. "Our results will have to be tested further for agronomic improvement by breeders. But narrowing down the pool of genes to those most likely influencing yield is an important step." The article, "Identification of crowding stress tolerance co-expression networks involved in sweet corn yield," is published in PLoS ONE. Martin Williams, an ecologist at USDA ARS and the University of Illinois, and Jenny Drnevich, a bioinformatics specialist at the University of Illinois, also contributed to the paper. More information: Eunsoo Choe et al. Identification of Crowding Stress Tolerance Co-Expression Networks Involved in Sweet Corn Yield, PLOS ONE (2016). DOI: 10.1371/journal.pone.0147418

News Article | November 18, 2016

Upcoming annual meetings of the Weed Science Society of America (WSSA) and regional weed science organizations are expected to offer new perspectives on a wide range of issues vital to the future – from how to manage herbicide-resistant weeds to new advances in weed control technologies. The WSSA’s annual meeting is scheduled for February 6-9, 2017, in Tucson, Arizona. The wide-ranging agenda includes multiple symposia and workshops. Among the topics are: •Precision Agriculture and Weed Science •Understanding and Reducing the Impact of Herbicide Off-Site Movement •Contributions of USDA ARS Area-Wide Projects to Weed Science Research and Practice •Navigating the New Landscape of Federal Funding for Weed Science Research •Teaching Undergraduate Weed Science: Strategies to Improve Learning Additional details and registration information are available online at the Society’s website. •Canadian Weed Science Society Meeting (CWSS), November 21-24, 2016 CWSS will hold its 70th annual meeting in Moncton, New Brunswick. One unique aspect of the program is an opening plenary session on “Forensic Weed Science.” Experts will use photographs of crop fields to review actual issues growers have encountered and discuss how to identify the cause. A wide range of learning opportunities are on the agenda, including regulatory reports, discussions of weed management in various crops, a session on the biology and ecology of invasive and noxious weeds, and a CropLife Resistance Management Panel on how industry and academia can work together to better support resistance management on the farm. Additional details and registration information are available at •North Central Weed Science Society (NCWSS), December 12-15, 2016 NCWSS will convene in Des Moines, Iowa, for its annual meeting. Further details will be posted soon at •Southern Weed Science Society (SWSS), January 23-25, 2017 The SWSS annual meeting is scheduled for Birmingham, Alabama. Registration information and meeting details will be posted soon at •Northeastern Weed Science Society (NEWSS), January 3-6, 2017 NEWSS will hold its annual meeting in Philadelphia, Pennsylvania. It also will host the second annual Northeastern Plant, Pest and Soils Conference. Details will be posted soon at •Western Society of Weed Science (WSWS), March 13-16, 2017 The WSWS annual meeting will be held in Coeur d'Alene, Idaho. Details will be posted soon at About the Weed Science Society of America The Weed Science Society of America, a nonprofit scientific society, was founded in 1956 to encourage and promote the development of knowledge concerning weeds and their impact on the environment. The Society promotes research, education and extension outreach activities related to weeds, provides science-based information to the public and policy makers, fosters awareness of weeds and their impact on managed and natural ecosystems, and promotes cooperation among weed science organizations across the nation and around the world. For more information, visit

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