Understand the trigger, not just the symptom
Downy mildew infection follows a known pattern: rain or dew, temperatures between 20–25°C, and wet leaf surfaces for a few hours. The oil-spot symptom appears days after infection has already happened. A programme built on weather windows will always beat one built on symptoms.
Bud break to pre-bloom
New growth is the most susceptible tissue in the vineyard. Begin protectant cover before the first forecast infection window. Combination products with systemic reach — such as Metalaxyl 8% + Mancozeb 64% WP at 600 g per acre — hold this stage through unsettled weather.
Bloom to berry set
This is the stage where infection costs the actual bunch, not just leaves. Keep spray intervals tight — 10 to 12 days in disease-favourable weather — and rotate modes of action. A strobilurin such as Azoxystrobin 23% SC at 200 ml per acre fits this window with both preventive and early curative action.
Do not apply more than two consecutive sprays of the same mode of action anywhere in the programme.
Berry development to harvest
Canopy management is disease management. Open canopies dry faster and shorten the leaf-wetness period the disease depends on. Observe pre-harvest intervals strictly — the export grade is tested, not assumed.
Note
Doses stated are indicative label rates. Always confirm against the product label and your local advisory before spraying. Use agrochemicals responsibly. Read the label before use.