Browsing by Author "Wallingford, Anna Kate"
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- Determining the threat of Pierce's disease to Virginia vineyardsWallingford, Anna Kate (Virginia Tech, 2008-07-10)Pierce's disease (PD) is a vascular disease of grapevines caused by Xylella fastidiosa (Wells et al.) (Xf) which is transmitted by xylophagous insect vectors. PD infection in Virginia vineyards was thought to be isolated to southeastern portions of the state as there have been no reports of vine loss in western Virginia and cold winter temperatures experienced there limit the effects of the bacterium from year to year. Upward trends in winter temperatures have raised PD concern in the mid-Atlantic. My risk assessment study found PD symptomatic vines beyond the modeled boundary for infection, confirmed Xf-positive with DAS-ELISA. Yellow sticky traps were used to survey Virginia vineyards throughout the 2006 and 2007 growing seasons to identify sharpshooter (Cicadellinae) species in six growing regions. Graphocephala versuta (Say) and Oncometopia orbona (Fabricius) (Hemiptera: Cicadellidae) were trapped in the greatest abundance and were both present in every region surveyed. This study uses geographical representation of climatological data to estimate risk for Pierce's disease.
- Investigating host plant selection of harlequin bug, Murgantia histrionica (Hahn), in order to improve a trap cropping system for its managementWallingford, Anna Kate (Virginia Tech, 2012-03-30)Harlequin bug (HB), Murgantia histrionica (Hahn), is a pest of cole crops. Alternative control strategies were investigated for control of HB, including trap cropping and systemic neonicotinoid insecticide applications. Potential trap crops, mustard (Brassica juncea "Southern Giant Curled" ), rapeseed (B. napus "Athena"), rapini (B. rapa) and arugula (Eruca sativa) were preferred over collard (B. oleracea "Champion"), and a non-brassica control, bean (Phaseolus vulgaris "Bronco") in field-cage choice tests. Harlequin bug could not complete development on bean, developed poorly on arugula but was found to complete development on mustard, collard, rapeseed and rapini. In the field, mustard was found to be an effective trap crop for reducing HB feeding injury on collard at three experimental sites in 2010 and 2011. Augmentation of the mustard trap crop with a systemic, neonicotinoid insecticide did not increase the level of control of harlequin bug for the duration of the ten week growing period. In olfactometer choice tests, male HB responded to plant volatiles of bean, collard and mustard, but preferred Brassica volatiles over those from bean. Female response to plant volatiles alone was weak and inconsistent. Both males and females preferred volatiles from other males feeding on Brassica host plant over plant volatiles alone, and were deterred by volatiles from males feeding on bean versus the plant alone. Laboratory toxicity assays revealed that the neonicotinoid insecticides imidacloprid, thiamethoxam, dinotefuran, and clothianidin were toxic to HB nymphs; LC50 = 0.57, 0.52, 0.39, and 0.39 mg ai/liter, respectively. Field experiments were conducted to evaluate the efficacy of these insecticides over time when applied as a one-time drench, and all were found to provide significantly higher mortality of HB for at least 14 days after application.
- The pest caterpillars of cole crops in VirginiaWallingford, Anna Kate; Kuhar, Thomas P.; Schultz, Peter B. (Virginia Cooperative Extension, 2012-03-02)Provides information about some of the butterfly and moth pests of Brassica oleracea (cabbage, broccoli, Brussels sprouts, etc.). Also notes some management options including cultural, biological and chemical controls.