Spray drift as a source of secondary deposition on the trees in orchards
2001
Holownicki, R. | Godyn, A. | Doruchowski, G. | Swiechowski, W. (Research Inst. of Pomology and Floriculture, Skierniewice (Poland))
The objective of this study was to determine the distribution of spray drift as a source of secondary deposition on adjacent trees during treatment in apple orchards and to evaluate its influence on biological efficacy of chemical thinning. The spray deposit of fluorescent tracer was evaluated on treated rows and on two downwind neighbouring rows. Cross-flow and directed air-jet discharge systems at two travel velocities (4.0 and 8.0 km per hour) and standard hollow cone and air injector nozzles were compared. The secondary deposition during blossoming and that at full leaf stage was significantly lower at 4.0 km per hour for the directed air-jet sprayer than for the cross-flow system in the second and the third row. The influence of secondary deposition was studied for the chemical thinning of fruitlets. The drift of spray from treated rows to two downwind rows caused significantly higher thinning effect on the downwind rows at 100 and 50 percent of the recommended dosage.
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