What causes powdery mildew in Marrow?

High humidity combined with poor air circulation Overcrowded planting conditions Warm days and cool nights Excessive nitrogen fertilisation promoting soft growth Water-stressed plants are more susceptible

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Powdery Mildew in Marrow

verifiedReviewed by the GreenScout Team

Marrow is a summer squash variety producing large, elongated green fruits that are harvested young and tender for optimal flavor and texture. A fungal disease that coats leaves, stems, and buds with a white or grey powdery substance. It rarely kills plants but weakens them significantly.

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Marrow care requirements

These care conditions are most relevant to powdery mildew in Marrow. Check each one as a potential cause.

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Light

Full sun (6–8 hours daily); essential for fruit production and preventing leggy growth.

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Water

Water regularly at soil level, providing 1–1.5 inches per week; increase frequency during fruit development. Keep soil consistently moist but not waterlogged.

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Soil

Rich, well-draining soil with ample organic matter; pH 6.0–7.0. Incorporate aged compost before planting.

symptoms

Symptoms to look for in Marrow

fiber_manual_recordWhite or grey powdery coating on leaf surfaces
fiber_manual_recordAffected leaves yellowing and curling
fiber_manual_recordDistorted or stunted new growth
fiber_manual_recordPowdery patches on stems and flower buds

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Common causes in Marrow

fiber_manual_recordHigh humidity combined with poor air circulation
fiber_manual_recordOvercrowded planting conditions
fiber_manual_recordWarm days and cool nights
fiber_manual_recordExcessive nitrogen fertilisation promoting soft growth
fiber_manual_recordWater-stressed plants are more susceptible

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How to diagnose powdery mildew in Marrow

The white powdery coating is distinctive — unlike downy mildew, powdery mildew sits on the upper surface of leaves and can be rubbed off with a finger.

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How to treat powdery mildew in Marrow

Remove and dispose of affected leaves. Spray with a diluted solution of baking soda (1 tsp per litre of water) or neem oil. Ensure good air circulation around the plant. In severe cases, use a fungicide labelled for powdery mildew.

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Preventing powdery mildew in Marrow

Space plants adequately for air flow. Avoid overhead watering. Do not over-fertilise with nitrogen. Water in the morning so foliage dries before evening.