This study was conducted over four seasons (2019: 2022), and its main objective was to control powdery mildew disease in grapes caused by the Uncinula necator. The control was carried out through a chemical control program, using agricultural fertilizers to reduce the number of fungicide sprays and completely control the disease.
In the first season, (2019) 11 different effective fungicides were tested after one spray application only, whether systemic or preventive, and their effect on disease severity % and crop characteristics of the plant was studied. In this respect, the results showed under Al Noubaria lactation that the beginning of the disease on the different grapevine varieties (Flam, Superior, Thomson) was five days after spraying. Generally, Amistar-Top (Azoxystrobin+ Difenoconazole) showed the best reduction of disease severity % on Flame verity (15 %). But, After 10 days of fungicide spray application. Flusilazole was the most efficient of fungicides in controlling the disease after 10 days of spraying and the best reduction of powdery mildew disease severity %on all varieties, Flame (30 %), Superior (45%), and Thomson (50%), respectively. In the second season (2020), 17 fungicides were been tested after 3 repeated spray applications every 10 days between the application and the following one. Eminent was the best on Superior verity that gave (330.0 g/ cluster). In the case of every 10 days application, Nimrod followed by Delata-Dom 25% Ec gave the highest weight of cluster (68.3 and 63.3gm/cluster) respectively. When testing agricultural fertilizers alone without fungicides, the best ones were chitosan and potassium sulfate. In the third season, (2021) a chemical program was designed in comparison with the farm program and proved its efficiency in reducing disease and raising crop characteristics. In the last season (2020/2021) the final program was applied, which combines preventive and systemic fungicides and agricultural fertilizers, and it proved its high efficiency in reducing disease severity compared to the farm program and general control.
Conclusively, the results showed that under the conditions of the El-Noubaria  region, Powdery mildew disease  showed on the different grape varieties (Flame, Superior, and Thompson) five days after  spraying. There were differences in the three varieties in their susceptibility to powdery mildew or their response to treatments with fungicides or fertilizers. In general, Amistar-Top (azoxystrobin + difenoconazole) showed the best reduction in disease severity % on the Film variety (15%). Eminent fungicide had the highest cluster weight on the Superior variety, giving (330.0 g/bunch). While, chitosan and potassium sulfate were the best efficiency as alternative fungicides. The final program was applied in the dormant stage, which have proven highly efficient in reducing the severity of the disease compared to the agricultural program and general control.