Azalea Petal Blight

Asked May 24, 2014, 12:26 PM EDT

What type of fungicide should I use on my azaleas that are suffering from petal blight? I see that the Azalea Society of America recommends benomyl, but the EPA says that product's registration was cancelled due to its health risks. Is there a product you recommend? Perhaps there is a natural remedy? It may be worth mentioning that these azaleas in question did not bloom at all last year. I read in a gardening book to pour a mixture of apple juice, epsom salt, and warm water around their base prior to the blooming season. I did this and they bloomed. However, now the blooms are brown, slimy, and stuck to the shrub...

New Castle County Delaware

2 Responses


Thank you for contacting Delaware Cooperative Extension. First I would want to make sure that your azaleas have petal blight and are not just senescing in the wet conditions we have had.
Ovulinia petal blight is caused by a fungus problematic on azaleas in humid areas, and is favored by wet, cool weather conditions during the flowering period. The symptoms are small light colored spots on colored petals. The spots look rusty on white cultivars. Spot become larger and flowers become soft and collapse. The petal blight fungus only attacks flowers. Petal blight occurs more frequently on mid- to late-season cultivars, and also occurs on rhododendrons.
Trim your azaleas after bloom this year, allowing for good air circulation. Fungicides for control are preventative, so mark this on your calendar for next year if weather is cool and rainy. A good fungicide to use might be one containing myclobutanil, applied according to the label when flower buds are expanding. Look for fungicides labeled for flowers, shrubs and trees.

My best,

I appreciate your response and will do all that you recommend. Thank you for your time and expertise.