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Florence-Graham, United States

Fortuna A.-M.,Washington State University | Honeycutt C.W.,U.S. Department of Agriculture | Vandemark G.,U.S. Department of Agriculture | Griffin T.S.,Tufts University | And 13 more authors.
Journal of Environmental Quality | Year: 2012

Soil biotic and abiotic factors strongly influence nitrogen (N) availability and increases in nitrification rates associated with the application of manure. In this study, we examine the effects of edaphic properties and a dairy (Bos taurus) slurry amendment on N availability, nitrification rates and nitrifier communities. Soils of variable texture and clay mineralogy were collected from six USDA-ARS research sites and incubated for 28 d with and without dairy slurry applied at a rate of ~300 kg N ha -1. Periodically, subsamples were removed for analyses of 2 M KCl extractable N and nitrification potential, as well as gene copy numbers of ammonia-oxidizing bacteria (AOB) and archaea (AOA). Spearman coefficients for nitrification potentials and AOB copy number were positively correlated with total soil C, total soil N, cation exchange capacity, and clay mineralogy in treatments with and without slurry application. Our data show that the quantity and type of clay minerals present in a soil affect nitrifier populations, nitrification rates, and the release of inorganic N. Nitrogen mineralization, nitrification potentials, and edaphic properties were positively correlated with AOB gene copy numbers. On average, AOA gene copy numbers were an order of magnitude lower than those of AOB across the six soils and did not increase with slurry application. Our research suggests that the two nitrifier communities overlap but have different optimum environmental conditions for growth and activity that are partly determined by the interaction of manure-derived ammonium with soil properties. © 2012 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. Source

Maxwell J.J.,Monsanto Corporation | Lyerly J.H.,North Carolina State University | Srnic G.,DuPont Pioneer | Murphy J.P.,North Carolina State University | And 5 more authors.
Crop Science | Year: 2012

Powdery mildew is a major fungal disease in wheat, especially in cool maritime climates. A novel Aegilops tauschii Coss.-derived wheat powdery mildew resistance gene present in the germplasm line NC96BGTD1 was genetically characterized as a monogenic trait in field trials using F 2- and F 4-derived lines from a NC96BGTD1 × 'Saluda' cross. Simple sequence repeat (SSR) markers were used to map and tag the resistance gene present in NC96BGTD1. Two dominant SSR markers flanking the resistance gene were identified. Xgwm635 mapped 5.5 and 8.3 cM distal to the resistance gene in the F 2 and F 4 generations, respectively. Xgpw328 mapped 16.2 cM proximal to the resistance gene in the F 2 and 13.6 cM proximal to the resistance gene in the F 4 generation. These SSR markers were previously mapped to the short arm of chromosome 7D and their positions were confirmed using Chinese Spring aneuploid and deletion stocks. Significant segregation distortion was observed in the F 4 generation with markers distal to the resistance gene showing a preference for the A. tauschii alleles while markers proximal to the resistance gene showed less significant preference for Saluda alleles. Only the adult plant resistance gene Pm38 has been mapped to the short arm of chromosome 7D but to a more proximal position than the gene in NC96BGTD1. The resistance gene described herein should be temporarily designated MlNCD1. © Crop Science Society of America. Source

Low temperature regular phosphine fumigations under the normal oxygen level and oxygenated phosphine fumigations under superatmospheric oxygen levels were compared for efficacy against the aphid, Nasonovia ribisnigri (Mosley), and effects on postharvest quality of romaine and head lettuce. Low temperature regular phosphine fumigation was effective against the aphid. However, a 3 d treatment with high phosphine concentrations of ≥2,000 ppm was needed for complete control of the aphid. Oxygen greatly increased phosphine toxicity and significantly reduced both treatment time and phosphine concentration for control of N. ribisnigri. At 1,000 ppm phosphine, 72 h regular fumigations at 6°C did not achieve 100% mortality of the aphid. The 1,000 ppm phosphine fumigation under 60% O2 killed all aphids in 30 h. Both a 72 h regular fumigation with 2,200 ppm phosphine and a 48 h oxygenated fumigation with 1,000 ppm phosphine under 60% O2 were tested on romaine and head lettuce at 3°C. Both treatments achieved complete control of N. ribisnigri. However, the 72 h regular fumigation resulted in significantly higher percentages of lettuce with injuries and significantly lower lettuce internal quality scores than the 48 h oxygenated phosphine fumigation. Although the oxygenated phosphine fumigation also caused injuries to some treated lettuce, lettuce quality remained very good and the treatment is not expected to have a significant impact on marketability of the lettuce. This study demonstrated that oxygenated phosphine fumigation was more effective and less phytotoxic for controlling N. ribisnigri on harvested lettuce than regular phosphine fumigation and is promising for practical use. © 2012 Entomological Society of America. Source

Hallman G.J.,USDAARS | Guo K.,Texas A&M University | Guo K.,Institute of Medical Plant Development | Liu T.-X.,Texas A&M University | Liu T.-X.,Northwest University, China
Journal of Economic Entomology | Year: 2011

Agromyzid leafminers are economic and quarantine pests of a variety of vegetables, flowers, and ornamental foliage. Methyl bromide fumigation is often used as a phytosanitary treatment when quarantined agromyzids are found in shipped commodities; alternative treatments are sought. Ionizing radiation is a viable alternative that is increasing in use worldwide. A dose of 400 Gy is accepted by USDA-APHIS for all insects (except Lepidoptera pupae and adults) on all commodities. Efforts to lower this dose and make it acceptable to other countries involve determining radiotolerance of families of major quarantine pests. Agromyzidae is one such family for which no useful information on radiotolerance exists. This research sought to determine the dose required to control a major agromyzid pest, Liriomyza trifolii (Burgess) and was performed on L. trifolii collected in Weslaco, TX, reared on Phaseolus vulgaris L. and Capsicum annuum L. and irradiated in the late puparial stage. The measure of efficacy was prevention of F1 mine formation. Puparia collected from Gossypium hirsutum L. and reared on P. vulgaris were more radiotolerant than those collected and reared on C. annuum. A dose of 214 Gy may prevent F1 mine formation of L. trifolii. This research used a variation of probit analysis where the direct response of the treated individual is not measured, but the response of the F1 generation is. This type of analysis is useful in phytosanitary irradiation research where the measure of efficacy often involves a response of the F1 generation. © 2011 Entomological Society of America. Source

Nansen C.,University of California at Davis | Elliott N.,USDAARS
Annual Review of Entomology | Year: 2016

Remote sensing describes the characterization of the status of objects andor the classification of their identity based on a combination of spectral features extracted from reflectance or transmission profiles of radiometric energy. Remote sensing can be benchtop based, and therefore acquired at a high spatial resolution, or airborne at lower spatial resolution to cover large areas. Despite important challenges, airborne remote sensing technologies will undoubtedly be of major importance in optimized management of agricultural systems in the twenty-first century. Benchtop remote sensing applications are becoming important in insect systematics and in phenomics studies of insect behavior and physiology. This review highlights how remote sensing influences entomological research by enabling scientists to nondestructively monitor how individual insects respond to treatments and ambient conditions. Furthermore, novel remote sensing technologies are creating intriguing interdisciplinary bridges between entomology and disciplines such as informatics and electrical engineering. © Copyright 2016 by Annual Reviews. All rights reserved. Source

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