White Spots / Powdery Mildew
White powdery patches on leaves are typically caused by powdery mildew, a common fungal issue. Other white spots may be mineral deposits or pest related.
可能原因
Powdery Mildew Fungus
Why: Thrives in warm, humid conditions with poor air circulation. Spreads via airborne spores.
Signs to check: White powdery coating on leaf surfaces, starts in patches and spreads, leaves may distort.
Hard Water Deposits
Why: Mineral-rich tap water can leave white crusty spots on leaves after misting or overhead watering.
Signs to check: Spots are crusty rather than powdery, appear where water droplets dried, can be wiped off.
Mealybug Residue
Why: Mealybugs produce white, cottony masses that can be mistaken for mildew.
Signs to check: White fluff concentrated at leaf joints and stem bases, sticky residue present.
檢查要點
- 1Try wiping the white substance — does it come off easily?
- 2Check if the coating is powdery (mildew) or crusty (mineral)
- 3Inspect for cottony clusters and sticky residue (mealybugs)
- 4Assess air circulation around the plant
處理方法
- Improve air circulation by spacing plants apart or using a fan
- Remove heavily affected leaves and dispose of them
- Avoid overhead watering and misting affected plants
- Apply a baking soda solution (1 tsp per quart of water) as a mild fungicide
- Use filtered water for misting to prevent mineral deposits
何時尋求幫助
- Mildew is spreading rapidly to other plants
- Leaves are yellowing, distorting, or dying beneath the coating
- Plant is losing vigor despite treatment
關鍵要點
Distinguish between fungal mildew, mineral deposits, and pests before treating. Improved air circulation is the best preventive measure.
在應用中跟蹤恢復
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來源: Missouri Botanical Garden, RHS. 內容根據公開可用的園藝參考資料編寫，僅供教育用途。列出來源組織僅為透明度考慮，並不意味著認可。