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My Lightning Bamboo Green (Pedilanthus tithymaloides, also called Euphorbia tithymaloides) feels well at my home; he already has a sprout.

So I can't explain what the white rash on the leaves are. It looks like white dots, but made of powder. I've already removed such leaves two days ago, but now other leaves have the same rash.

Do you know what could be causing the white rash on the leaves?

Pedilanthus tithymaloides White rash on Pedilanthus tithymaloides

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up vote 5 down vote accepted

I'm going to stick with my initial thought, Powdery Mildew as the culprit.

  • Powdery Mildew via University of Illinois Extension

    • Gives: Description, Symptoms and Control (Nonchemical & Chemical).

  • Podcast - Powdery Mildew via University of Illinois Extension

Richard Hentschel interviews with Jim Schuster, form Extension plant pathologist about powdery mildew, a typical disease of the late summer that has showed up much earlier this year due to the high humidity and night temperatures. Cultural management includes proper location and thinning in the spring and possible fungicide treatments.

This is general listing of active ingredients labeled for use for control of powdery mildew. Always consult the label to make sure both the host and disease are listed

Sodium bicarbonate commonly known as baking soda has been found to posses fungicidal properties. It is recommended for plants that already have powdery mildew to hose down all the infected leaves prior to treatment. This helps to dislodge as many of the spores as possibly to help you get better results. Use as a prevention or as treatment at first signs of any of the diseases.

To make:

  • Mix 1 tablespoon baking soda

  • 2½ tablespoons vegetable oil with one gallon of water.

  • Shake this up very thoroughly.

  • To this mix add ½ teaspoon of pure Castile soap and spray.

  • Be sure to agitate your sprayer while you work to keep the ingredients from separating. Cover upper and lower leaf surfaces and spray some on the soil.

  • Repeat every 5-7 days as needed.

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Yes, powdery growth without an obvious source (eg. Sawdust from insects or DIY work) is almost certainly some kind of fungi. – winwaed Oct 25 '11 at 22:54

It sounds like your plant is not getting enough water. From this article:

Be careful with the draught., which will cause mildew with a white fluffy deposit on the stems and leaves.

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