The subject of the study was to determine the potential for reducing dose of Sokół 460 EC preparation used in the prevention and combating powdery mildew oak. The study was conducted on one-year common oak seedlings in a nursery field conditions. To determine the degree of infestation software CompuEye – Leaf was used and symptom area, too. The research material in the form of assimilation apparatus derived from the summer increase harvested in mid-September forming separately, for each variant and collective attempt, to block consisting of 10–13 leaves sample and then every attempt was scanned in accordance with the requirements of the software. Next, for each sample cumulative level of infestation was determined expressed as a percentage of the area showing symptoms of infection by powdery mildew oak. The obtained results allow to exclude (at five times the number of treatments) possible reduction below the recommended dose for one-year seedlings of oaks.

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