Ask the Plant Doctor! How much to water, composting and common fungal diseases

Spray insecticidal soap to get rid of powdery mildew on plants. Photos: 123rf.com

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Several reasons can lead to the appearance of white dust or talcum-like powder on your plants. However, your observation that your rose plant is especially vulnerable suggests that powdery mildew could be the problem. This common fungal disease affects many plants, with roses being particularly susceptible.