Wirkung von Fungiziden gegen Rostkrankheiten des Weizens in Abhaengigkeit von der Applikationstechnik. 2. Feldversuche.
1992
Haden E. | Grossmann F.
In a 4-year research project, different application techniques were tested for their suitability for spraying rust fungicides. Some of the techniques were still in the experiment stage. By using smaller nozzles which were slanted in front 20 degrees out of the horizontal niveau or combined with electrostatical droplet-charging and especially by using electrostatically charged spinning-disc-sprayers, the spray volume could be reduced to a considerable extent in comparison to conventional techniques. The area treated per time unit with the spraying devices and the biological efficacy were not changed. The processes and spraying devices tested led to higher deposits on the target surfaces ear, flag leaf and second-highest leaf as compared to conventional spraying techniques. Before emergence of the ears, treatments with electrostatically charged droplets resulted in significantly higher deposits on the flag leaf. Treatments with the charged spinning-disc-sprayer proved to be significantly better than those with electrostatically charged flat-fan-nozzles slanted in front. The differences in the deposits achieved between these treatments resulted in corresponding differences in the biological efficacy. After emergence of the ears, all techniques produced higher deposits of fungicides on the flag leaf as compared to the spraying devices used in practice. Under the experimental conditions selected, the higher deposits did not result in a better biological efficacy. The retention rates on the ears showed positive differences in favour of the variants with slanted sprayboom. Reduced amounts of fungicides per hectare were chosen for methodical reasons. The biological efficacies achieved with those amounts were not sufficient even by using the new technologies.
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