Common crops affected
What is it?
Powdery mildew is caused by fungi in the order Erysiphales. Unlike most fungal diseases it does not need leaf wetness to take hold, so it appears even in dry weather — especially in dense, shaded, poorly ventilated plantings with warm days and cool nights. The fungus draws nutrients from the plant, reducing photosynthesis, vigor, and crop quality.
How to identify it
- White or grayish powdery patches, usually starting on the upper leaf surface
- Patches spread and merge until leaves look dusted with flour
- Leaves may yellow, curl, twist, or drop early
- In severe cases, stems, buds, and fruit are coated
- New growth is often most affected and may be distorted
Damage and how it spreads
Powdery mildew spores spread on wind and germinate quickly in crowded canopies. Left unchecked it reduces photosynthesis and vigor, causes early leaf drop, and lowers yield and fruit quality — in grapes and cucurbits it can be economically serious. Because it spreads fast, early action matters.
How to control it
- Remove and dispose of affected leaves (in the trash, not the compost).
- Improve air circulation — space plants, prune dense growth, and avoid excess nitrogen.
- Water at the base early in the day, not overhead.
- Treat at the first sign and, on susceptible crops, continue preventively.
Recommended Vegalab solution: Mildew Control
Vegalab Mildew Control is an all-natural mildew treatment powered by Geraniol 17%. It has a two-fold action: it retards spore germination and germ-tube growth, and destroys pathogen cells by inducing a K+ ion imbalance in the mycelium. It is most effective preventively but gives curative action on early outbreaks. Apply as a foliar spray at disease onset, diluted 1:2,000 (0.5 mL/L). It is proven on grapes, cucurbits, apples, brambles, and tomatoes. For broad mixed disease pressure, Spore Control (Thymol) is a broad-spectrum companion.
| Role | Product | Use |
|---|---|---|
| Primary control | Mildew Control | Geraniol fungicide for mildews |
| Companion / broader pressure | Spore Control | Broad-spectrum protective fungicide |
| Plant support | Armour Boost | Silica for tissue resilience |
Preventing it next season
Choose resistant varieties where available, keep canopies open, and start a preventive program before symptoms appear on high-risk crops. Stronger plants resist infection — Armour Boost (silica) helps build more resilient tissue.
Claims and product availability vary by jurisdiction. Always read and follow the product label.