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Pascal Braekman, Dieter Foqué, Marie-Christine Van Labeke, Jan G. Pieters, and David Nuyttens

Gilles (1992) showed that an electrostatic reduced-volume application of permethrin insecticide to greenhouse-grown chrysanthemums resulted in significantly higher spray deposition compared with the conventional high-volume application. However, this

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Ockert P.J. Stander, Jade North, Jan M. Van Niekerk, Tertia Van Wyk, Claire Love, and Martin J. Gilbert

, it is unclear how the covering of trees with NPN before, during, and after flowering for an extended period, thereby affecting tree growth and fruit development, impacts the deposition of foliar sprays that are applied and fruit production. This study

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Gary VanEe, Richard Ledebuhr, Eric Hanson, Jim Hancock, and Donald C. Ramsdell

Most highbush blueberries (Vaccinium corymbosum L.) in Michigan are treated annually with fungicides and insecticides with several types of sprayers. The goal of this study was to determine how sprayer type, pruning severity, and canopy development interact to affect spray deposition patterns. Deposition was measured as the percentage of the surface area of card targets that was covered following applications of black dye. Light measurements indicated that the canopy of blueberry bushes, regardless of pruning treatment, closed by the middle of June, and light levels within the canopy changed little from then until fruit harvest in August. A standard airblast sprayer that pushed spray up and through bushes provided acceptable deposition in all parts of the canopy early in the season, but later in the season, coverage was poor in the top and sides furthest from the sprayer. An above-row sprayer with fan-driven micronozzles also provided acceptable coverage throughout the bushes early in the season, but once the canopy had closed, coverage was poor in the bottom of the bush. Both sprayers were operated in bushes receiving light, moderate, and heavy pruning. The more severe pruning regimes increased the amount of spray deposited from the above-row sprayer, but not from the airblast sprayer.

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Ed Stover, Dominick Scotto, Chris Wilson, and Masoud Salyani

Foliar application of spray materials is an integral component of commercial citrus production. An intensive assessment of spray application practices has been stimulated by low fruit value and increased concern about potential surface water contamination in the Indian River citrus region of Florida. Many publications report research results regarding distribution of spray materials within orchards and off-target deposition, but interpretation is challenging because so many factors influence spray results, and integrating this information into practical recommendations is difficult. Canopy geometry and density are prominent factors contributing to variable deposition and spray drift. Environmental factors such as temperature, relative humidity, wind speed, and wind direction also greatly influence spray deposition and drift, and substantial changes can occur within seconds. In addition the physical and/or mechanical set up of the sprayer interact significantly with the other factors. A better understanding of these interactions should help growers optimize spray effectiveness and efficiency while reducing potential off-target effects.

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Ed Stover, Chris Wilson, Dominick Scotto, and Masoud Salyani

Parts I and II of this series revealed substantial opportunities for improving spraying of Indian River citrus (Citrus spp.). In this segment of our work we develop guidelines for growers to select the spray parameters providing an optimal balance between efficiency and efficacy while minimizing environmental contamination.

It is proposed that these guidelines could be codified in a simple expert system to make them easier to use. We propose that understanding limiting conditions may be the key to choosing spray options. Wind is a major factor influencing spray deposition and offtarget drift. Based on weather records, wind speeds below 5 mph (8.0 km·h-1) are only routinely observed from 2000 HR until 0800 HR, making night spraying a good choice for low-volume applications. The importance of adjusting sprayer set-up for individual groves is demonstrated, with economic estimates of the cost of failing to make these adjustments. Routine use of careful sprayer adjustments is also likely to reduce off-target drift. Improvements in equipment and spray chemicals are also discussed. Use of non-orchard buffer areas and/or windbreaks appear to offer considerable opportunity for reducing off-site spray movement.

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Dieter Foqué, Jan G. Pieters, and David Nuyttens

insufficient deposition on the underside (or abaxial) of the leaves. These findings confirm that using a higher spray volume or pressure cannot guarantee better spray results. As a reaction to insufficient pest control, the growers usually spray more frequently

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

strategies, confirmation of the actual spray coverage and spray deposition on targets under field conditions is required ( Bache and Johnstone, 1992 ). The spray coverage required to effectively control pests has been studied for other crops ( Falchieri et al

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S.J. McArtney and J.D. Obermiller

delivering an equivalent total spray volume. Foliar spray deposition was determined by placing three WSP at each of six different heights in the test tree. Spray coverage was assessed by image analysis of water-sensitive papers (WSP; Spraying Systems) stapled

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Vladimir Orbović, Diann Achor, and James P. Syvertsen

Copper (Cu) is an important component of the fungicide programs that are used for control of many important diseases of citrus. Copper-based fungicides, used either alone or with spray oil, can successfully control greasy spot, melanose, citrus