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Pests & Diseases > Powdery Mildew


This is a common problem, particularly for eucalypts. It will appear as a whitish or purple powdery substance on the leaves and stems or brown spots on the leaves. Advanced attacks of Powdery Mildew will damage the young emerging leaves and eventually kill the plant.

It is generally a cooler-month problem, caused by too much moisture remaining on the plant, particularly overnight. The temperature is not warm enough for the moisture to evaporate. It also occurs if the seedlings are in too much shade or if they have not been thinned, preventing air circulation around the individual seedlings.


Early stages of mildew will usually only set back a plant, rather than kill it; however you will need to act quickly, remove and discard any badly affected seedlings. Keep foliage dry in cool weather, particularly at night; ensure the seedlings are in full sun and make sure that you thin out the seedlings early enough.


You can buy mildew products at your local garden shop. Follow directions carefully.

You can also use a milk solution, mixing 1 part whole milk to 5 parts water which you directly spray onto the affected areas every second day.