Pests, diseases and hormones: ask before you spray
Remove loose bark at pruning to stop pests laying eggs. The source lists chemical sprays for flea beetles, nematodes, powdery mildew, downy mildew, anthracnose, rust and bacterial leaf spot, and a schedule of growth hormones (GA3 and others) for berry size. Hormone timing and dose are critical — for example, the source warns against GA3 in cloudy weather and from full bloom to fruit set. Choose any product only with your local Horticulture Officer.
Follow the instructions on the product label. Consult your local Agriculture Officer before use.
Pending expert review
Source
Crop Production Guide – Horticulture Crops 2020 (Directorate of Horticulture and Plantation Crops, Tamil Nadu & Tamil Nadu Agricultural University (TNAU)), Grapes – Plant protection; quality improvement, pp. 24–27
