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M.J. Bukovac and D.L. Reichard

Most growth regulators and crop protection chemicals are delivered to the plant as aqueous sprays. Spray droplet:plant surface interaction is central to establishing spray and, hence, dose retention by the plant. Further, the nature of chemical deposition from spray droplets plays an important role in determining the efficiency of the active ingredient (a.i.). Using scanning electron microscopy and dispersive x-ray analysis, we investigated chemical deposit formation of selected growth regulators (e.g. ethephon, 2,4, 5-TP, TIBA) on leaf surfaces differing in wettability and surface fine-structure. The a.i. frequently deposited in the form of an annulus on droplet drying, and the degree of spreading was related to surface tension of the spray solution, and wettability, fine-structure and morphology of the leaf surface. Marked differences were observed in spreading following impaction on veins vs. interveinal areas of leaves of Prunus and Pyrus sp. The epidermis over veins was more readily wetted leading to rapid lateral diffusion along veins. Surfactants (e.g. Tween 20, Regulaid) altered the deposition pattern, expanding the annulus and increasing spreading on the leaf surface.

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Martin J. Bukovac

. Sabbatini, and G. Sorrenti, Michigan State University, for technical assistance; D.L. Reichard, H.J. Retzer, R.D. Brazee, and J.A. Cooper, USDA Agricultural Research Service, for assistance with droplet measurements; and R.E. Whitmoyer, Electron Microscope

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Clint Hoffmann, Brad Fritz, Dan Martin, Ryan Atwood, Tim Hurner, Mark Ledebuhr, Matt Tandy, John L. Jackson, and Gail Wisler

respond to the need to treat large numbers of acres repeatedly in a timely manner. These machines can produce droplets with volume median diameters that range from 5 to 210 μm, depending on spray solution and equipment setup ( Hoffmann et al., 2007a ). The

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Larissa Larocca de Souza and Marcelo L. Moretti

environment and spray equipment ( Kudsk, 2002 ). Carrier volume and droplet size are spray quality parameters that can interfere with herbicide efficacy. It is well established that spray coverage improves with increasing spray volume—to a point. In broad

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Vladimir Orbović, Diann Achor, and James P. Syvertsen

reduced surface tension of solutions and, in some cases, increased penetration through open stomata ( Field et al., 1992 ). Singh and Singh (1995) described the ability of L-77 to decrease contact angles of droplets of solution leading to enhancement of

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Jean Carlos Bettoni, Aike Anneliese Kretzschmar, Remi Bonnart, Ashley Shepherd, and Gayle M. Volk

procedures using a limited number of species ( Bi et al., 2017 ). So far, the droplet vitrification technique appears to be a promising method to overcome species-specific and genotype-specific responses to Vitis cryopreservation ( Bi et al., 2018a ; Volk

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John E. Kaminski and Michael A. Fidanza

, spray pattern, and water-droplet size ( Armstrong-Cho et al., 2008 ; Chapple et al., 1997 ; Jensen et al., 2001 ; Lesnik et al., 2005 ). In creeping bentgrass, Couch (1985) reported that a localized penetrant fungicide dispersed in a flat-fan spray

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Heping Zhu, James Altland, Richard C. Derksen, and Charles R. Krause

coverage was based on the ratio between the area covered by spray deposits and the total area of a water-sensitive paper. The number of droplets per unit area was also reported as the droplet density on the target. The spray coverage on each water

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Atsushi Kono, Akihiko Sato, Bruce Reisch, and Lance Cadle-Davidson

shaking, suspensions were shaken by hand, and 3 μL of suspension was sampled to count sporangia by the dried droplet method as described below. Estimated log10-transformed mean concentrations of each Tween 20 concentration were separated by Tukey’s all

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Weiping Zhong, Zhoujun Zhu, Fen Ouyang, Qi Qiu, Xiaoming Fan, and Deyi Yuan

the accumulation of large amounts of nutrients before germination, usually starch or lipid droplets. These changes in the nutritional components are closely related to pollen development. The duration and type of nutrient accumulation in anthers vary