AN IMPROVED APPLE TREE DISEASE PROTECTION SYSTEM FOR THE HUMID SUBTROPICS ON THE BLACK SEA СOAST OF THE СAUCASUS

The apple tree is a traditional crop on the Black Sea coast of the Caucasus, but successful cultivation of this crop is hampered by intensive leaf and fruit diseases such as scab, powdery mildew and moniliosis. The following fungicides have traditionally been used in the apple tree protection system against diseases in the region: Scor, CE (diphenoconazole), Topaz, CE (penconazole) and Strobitek, VDG (cresoxime-methyl). The existing cultural protection system has been in use for more than twenty years and has ceased to be effective. The experience of improving apple trees protection against dominant diseases was carried out on the Golden Rangers cultivar in the experimental farm of the Institute of Agriculture of the Academy of Sciences of Abkhazia (Gulrypshsky district, the Republic of Abkhazia) in 2023–2025. The improved apple tree protection system includes fungicides from different chemical groups: Miravis, SC (pidiflumetophene), Luna Tranquility, CS (fluopyram + pyrimethanyl), Zato, VDG (trifloxystrobin) and Polyram DF, VDG (metyram). During the growing seasons in 2023–2025, the intensity of powdery mildew development on apple trees in the control variant reached 18.5–32.0 %. The variant of the traditional protection system restrained the development of diseases: powdery mildew – at the level of 4.8–13.5 %, fruit scab – at the level of 9.8–15.5 %, monilial rot – at the level of 5.8–14.2 %. The use of the new protection system restrained the intensity of disease development at a level not exceeding 4.2–7.0 %. The biological effectiveness of the traditional protection system did not exceed 74.0 %, which is considered a low indicator for industrial gardens. The biological efficiency of the improved apple tree protection system was 81.0–90.6 % for leaf powdery mildew, 81.2–85.4 % for fruit scab and 76.0–87.6 % for monilial rot of fruits. The new plant protection system significantly increased crop yields by 7.9–8.7 % compared to the reference version.