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Maynardville, TN, United States

Hadley T.L.,University of Tennessee at Knoxville | Grizzle J.,University of Tennessee at Knoxville | Rotstein D.S.,University of Tennessee at Knoxville | Rotstein D.S.,National Oceanic and Atmospheric Administration | And 8 more authors.
Journal of Avian Medicine and Surgery | Year: 2010

Aflatoxin B1 is a common hepatotoxin in birds. The goal of this study was to establish an acute model for hepatotoxicosis and decreased hepatic function in the white Carneaux pigeon (Columba livia) via oral administration of this mycotoxin. Aflatoxin B1 was orally administered at a dose of 3 mg/kg dissolved in dimethyl sulfoxide to 3 groups of pigeons every 24 hours for 2, 4, and 6 consecutive days, respectively. Diagnostic modalities used to evaluate hepatic damage and impaired hepatic function pre- and postaflatoxin administration included liver enzyme activity, bile acid levels, scintigraphy, and histopathologic evaluation of liver biopsy specimens. Deaths occurred in all groups, increasing with the number of consecutive days the aflatoxin B1 was dosed. Significant histopathologic lesions were seen on evaluation of hepatic tissue from each group after accumulated aflatoxin exposure (P < .05); therefore, an oral aflatoxin B1 dose of 3 mg/kg given for 2 consecutive days was selected for the purpose of inducing acute hepatic damage while minimizing mortality. However, although increased liver enzyme activity indicated hepatocellular damage at this dosage, bile acids testing and hepatobiliary scintigraphy did not show significantly decreased hepatic function. © 2010 by the Association of Avian Veterinarians. Source

Cheng Q.,University of Tennessee at Knoxville | Windham A.S.,University of Tennessee Extension | Klingeman W.E.,University of Tennessee at Knoxville | Sakhanokho H.F.,U.S. Department of Agriculture | And 3 more authors.
Canadian Journal of Plant Pathology | Year: 2011

The infection process of Discula destructiva Redlin on Cornus florida L. leaves was studied using histological and microscopic techniques. Penetration of fungal hyphae through natural openings and wounds was not observed, while direct penetration without appressorium formation was demonstrated 3 days after inoculation (DAI). Leaves inoculated with D. destructiva developed symptoms of dogwood anthracnose after 7 to 8 days. At 8 DAI, hyphae were observed in aggregations located between the cuticle and epidermis and also growing intracellularly towards epidermal, palisade, parenchymal and spongy mesophyll cells. At 16 DAI, typical chlorotic and necrotic halos, with a red to purple external border, were formed on the inoculated leaves. Within leaf tissues, at 16 DAI, chloroplasts were intact but decompartmentalized and infection sites were clearly defined. Sporulation and ruptured acervuli (cuticle ruptured and spores released) were first detected at 20 DAI, and had fully developed to rupture the plant cuticle on both adaxial and abaxial leaf surfaces by 24 DAI. © 2011 The Canadian Phytopathological Society. Source

Koepke-Hill R.M.,University of Tennessee at Knoxville | Armel G.R.,University of Tennessee at Knoxville | Klingeman W.E.,University of Tennessee at Knoxville | Halcomb M.A.,University of Tennessee Extension | And 2 more authors.
HortTechnology | Year: 2011

Field and greenhouse studies were conducted to determine if two indole- 3-acetic acid herbicide mimics, aminopyralid and aminocyclopyrachlor-methyl, applied at 70, 140, and 280 g.ha -1 postemergence (POST) would control mugwort (Artemisia vulgaris) in an abandoned nursery. These were compared with the commercial standards picloram at 280 g.ha -1 a.i. and clopyralid at 280 g.ha -1. In the field study, picloram and clopyralid controlled mugwort 75% and 31% by 365 days after treatment (DAT), respectively. In contrast, aminopyralid and aminocyclopyrachlor- methyl applied at 140 g.ha -1 controlled mugwort over 90% by 365 DAT. In the greenhouse study, aminopyralid and aminocyclopyrachlor-methyl applied at 140 g.ha -1 controlled mugwort 92% and 96% respectively, although aminopyralid at 70 g.ha -1 provided better visual control (94%) in comparison with aminocyclopyrachlor- methyl (79%) at 70 g.ha -1. Regardless, following shoot growth removal at 30 DAT, mugwort failed to regrow by 60 DAT following exposures to all rates of both herbicides. On the basis of these studies, aminopyralid and aminocyclopyrachlormethyl have potential to provide excellent control of mugwort compared with the current standards clopyralid and picloram. © 2011 by the American Society for Horticultural Science. Source

Cutulle M.A.,University of Tennessee at Knoxville | Armel G.R.,University of Tennessee at Knoxville | Brosnan J.T.,University of Tennessee at Knoxville | Kopsell D.A.,University of Tennessee at Knoxville | And 6 more authors.
HortTechnology | Year: 2013

Selective weed control in ornamental plant production can be difficult as many herbicides can cause unacceptable injury. Research was conducted to evaluate the tolerance of several ornamental species to applications of p-hydroxyphenylpyruvate dioxygenase (HPPD)-inhibiting herbicides for the control of problematic weeds in ornamental production. Mestotrione (0.09, 0.18, and 0.36 lb/acre), tembo- trione (0.08, 0.16, and 0.32 lb/acre), and topramezone (0.016, 0.032, and 0.064 lb/acre) were applied alone postemergence (POST) in comparison with the photosystem II-inhibiting herbicide, bentazon (0.5 lb/acre). All herbicide treatments, with the exception of the two highest rates of tembotrione, caused less than 8% injury to 'Noble Upright' japanese holly (Ilex crenata) and 'Compactus' burning bush (Euonymus alatus). Similarly, no herbicide treatment caused greater than 12% injury to 'Girard's Rose' azalea (Azalea). Conversely, all herbicides injured flowering dogwood (Cornusflorida) 10% to 23%. Mesotrione- and tembotrione- injured 'Radrazz' rose (Rosa) 18% to 55%, compared with only 5% to 18% with topramezone. 'Siloam June Bug' daylily (Hemerocallis) injury with topramezone and tembotrione was less than 10%. Topramezone was the only herbicide evaluated that provided at least 93% control of redroot pigweed (Amaranthus retroflexus) with all application rates by 4 weeks after treatment (WAT). Redroot pigweed was controlled 67% to 100% with mesotrione and tembotrione by 4 WAT, but this activity was variable among application rates. Spotted spurge (Chamaesyce maculata) was only adequately controlled by mesotrione applications at 0.18 and 0.36 lb/acre, whereas chamberbitter (Phyllanthus urinaria) was not controlled sufficiently with any herbicide evaluated in these studies. Yellow nutsedge (Cyperus esculentus) was suppressed 72% to 87% with mesotrione applications at 0.18 lb/acre or higher and with bentazon at 0.5 lb/acre by 4 WAT. All other herbicide treatments provided less than 58% control of yellow nutsedge. In the second study, 'Patriot' hosta (Hosta), 'Green Sheen' pachysandra (Pachysandra terminalis), autumn fern (Dryopteris erythrosora), 'Little Princess' spirea (Spiraea japonica), 'Green Giant' arborvitae (Thujaplicata), and 'Rosea' weigela (Weigelaflorida) displayed no response to topramezone when applied at 0.024 and 0.095 lb/acre. Since 10 ornamental species in our studies exhibited less than 10% herbicidal response with all rates of at least one HPPD-inhibiting herbicide then it is possible that these herbicides may provide selective POST weed control in ornamental production systems. Source

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