Advances in apple cultivation, aiming to maximize the efficiency of harvest and yield per hectare, have led to the development of high-density apple orchards. High density orchards are characterized by densely planted narrow fruiting rows, with a “hedgerow” appearance. Whilst modern apple production has led to changes in orchard architecture, the technology used to apply agrochemicals has remained largely the same. The most commonly used technology to apply agrochemicals in apple orchards is the axial-fan Airblast sprayer. Unfortunately, these large, fan assisted sprayers were designed to treat larger more voluminous canopies leading to off target drift. An alternative spraying technology, the solid set canopy delivery System, or the SSCDS is a series of spray emitters placed in or above the canopy, making applications without the assistance of a large fan. Research into the plausibility of the SSCDS indicates that these systems are able to reduce off target drift while providing pest management equivalent to the commonly used axial-fan Airblast sprayer. A majority of the solid set systems assessed place emitters in the canopy which increases the chances for damage or emitter occlusion. The above canopy configuration reduces these chances, placing emitters overhead. This research was to quantify losses to ground as well as vertical and downwind off target drift produced by an above and in canopy SSCDS configuration compared to an axial-fan Airblast sprayer. Additionally, my research assessed the coverage, and deposition provided by two SSCDS configurations as well as season-long pest management, and fruit quality in orchards treated by an in canopy and above canopy SSCDS as well as a axial-fan Airblast sprayer. Off target drift measures suggest that vertical as well as downwind off target drift are significantly lower compared to drift produced by an axial-fan Airblast sprayer. Deposition measures indicated that both SSCDS configurations provided equivalent deposition throughout the canopy. Coverage however was greater at the top of the canopy and adaxial surfaces in trees treated by the above canopy SSCDS while coverage was more evenly distributed through the canopy in trees treated by the in canopy SSCDS. Pest management evaluations conducted in 2019 and 2020 detected little arthropod or disease damage in apples or foliage, damages similar in all treatments. Fruit quality assessments, including: size, weight and fruit count did detect differences between the SSCDS and axial-fan Airblast applications. The SSCDS configurations failed to adequately thin, apples leading to higher fruit counts in SSCDS treated trees. However estimated yield was not affected with similar metric tonnage per hectare determined for each treatment. These results suggest both the above canopy and in canopy SSCDS configurations produce significantly less off target drift compared to an axial-fan Airblast sprayer while providing adequate, equivalent pest management when compared to an axial-fan Airblast sprayer.
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