Zantedeschia Captain Signum White Powder - Causes & Fixes

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Powdery Mildew

A fungal disease caused by pathogens like Podosphaera takii, which thrives in humid conditions with poor air circulation. It presents as a white, flour-like coating on the leaves of Zantedeschia, eventually leading to yellowing and leaf necrosis.

Very Common

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How to confirm: Check if the white spots can be rubbed off easily with your finger or if they appear more concentrated on the underside of the leaves.

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1 Apply an organic fungicide to eliminate the existing fungal spores and prevent further spread across the leaves.

Bonide Captain Jack's Copper Fungicide 32 oz

0.9 L • 1 pcs • Organic

$12

In Stock

2 Improve air circulation around the plant and reduce humidity by avoiding overhead watering, which helps prevent the pathogen from thriving.

3 Prune and dispose of any heavily infected leaves to prevent the fungus from spreading to healthy parts of the Calla Lily.

Fiskars 5/8" Bypass Pruning Shears

Cutting Tools

$13

In Stock

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Mineral/Salt Residue

Accumulated calcium, magnesium, or salts from hard water or excessive fertilizer can leave a white, crusty residue on the leaf surface. This is common in Calla Lilies if they are watered with tap water containing high mineral content.

Common

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How to confirm: Wipe a leaf with a damp cloth; if the white substance dissolves or disappears, it is likely mineral buildup rather than a pathogen.

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1 Gently wipe the leaves with a soft, damp cloth using distilled or filtered water to remove the mineral buildup without damaging the plant tissue.

2 Flush the soil thoroughly with distilled water or rainwater to leach out accumulated salts and prevent further residue buildup.

3 To prevent future nutrient imbalances, use a balanced liquid fertilizer and monitor soil levels with a moisture meter to avoid over-fertilizing.

GROWIT Soil Moisture Meter - Blue

Water Meters

$12

In Stock

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Mealybugs

Small, soft-bodied insects that secrete a white, waxy, cotton-like substance to protect themselves. They often congregate at the base of the flower spathe or where the leaf meets the stem in Zantedeschia.

Common

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How to confirm: Inspect the crevices of the plant for tiny, moving white clusters or sticky residue (honeydew) on the leaves.

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1 Isolate the plant immediately to prevent the mealybugs from spreading to your other houseplants.

2 Treat the visible white waxy clusters by spraying the plant with an organic insecticide/miticide to kill the insects and their eggs.