I have what appears to be rust on my azalea bushes. The leaves are whitish with some splotches of red as well. I have both evergreen and exbury variet...
Knowledgebase
Azalea Disease #592068
Asked August 25, 2019, 9:45 PM EDT
I have what appears to be rust on my azalea bushes. The leaves are whitish with some splotches of red as well. I have both evergreen and exbury varieties, both of which are showing similar symptoms. What is the best remedy for bringing these plants back to a healthy appearance again?
Clackamas CountyOregon
Expert Response
Thank you for your question. I suspect you have an infestation of the azalea lace bug, described here: http://oregonstate.edu/dept/nurspest/Azalea_lacebug.pdf
You can look on the undersides of the leaves and find the black spots. Let me know what you find!
I don't see any azalea lace bugs on the underside of the leaves but there are numerous black spots. The attached photo shows the underside of the leaves -- exbury azalea on the left and evergreen on the right. Assuming this is damage from the lace bug, what is the best remedy?
I don't see any azalea lace bugs on the underside of the leaves but there are numerous black spots. The attached photo shows the underside of the leaves -- exbury azalea on the left and evergreen on the right. Assuming this is damage from the lace bug, what is the best remedy?
Since there are several generations of lace bugs each year, not finding an insect isn’t unusual. They’ve flown off! The article that I linked you to has the only control mechanisms available. Unfortunately, there are no ‘silver bullets’ for them.
I have a total of five azalea bushes that are planted in close proximity to each other. All of them display signs of lace bug infestation. Two of them are an exbury variety that are now starting to drop their leaves. The other three are an evergreen variety.
With fall and winter weather approaching I assume the lace bugs will not be present until next spring. Can you recommend anything I can do between now and then to prevent another infestation next year and to get them healthy again?
As the article to which I referred you to indicates, your plants have eggs on the leaves that overwinter there, and "The egg stage is embedded in the plant material and thus protected from most control (except for horticultural oils). Most of the remaining chemical options act either as contact insecticides such as the pyrethroids or carbaryl or have systemic activity such as acephate or the neonicotinoids. Contact insecticides and some of the systemic insecticides may have a detrimental impact on beneficial insects. Timing of the neonicotinoid insecticides generally is either a foliar application shortly before the egg hatch (6-8 weeks) or applied as a soil drench in the late fall."
Sorry nothing else has been discovered since you first wrote.
Neem oil is an organic pesticide, derived from the neem tree, that lives primarily in India, but also some Western African countries. It is an insecticide (kills insects by suffocating them), a miticide (kills mites the same way), and a fungicide (kills fungi, which are very similar to animals by taking in oxygen and giving off carbon dioxide.) A very good pesticide to become aware of. Here is a longer article on this: http://npic.orst.edu/factsheets/neemgen.html
