Care of Magnolia Trees With Black Leaves
A common cause of black leaves on magnolia trees is sooty mold. This black powdery mold actually doesn't feed on the plant. Instead, it feeds on honeydew, a sticky substance excreted by the magnolia scale. Scales are immobile, round and covered in white waxy filaments. They attach to leaves and branches and suck sap from the tree. In order to get rid of sooty mold, you'll need to get rid of the magnolia scale. Once the scale insects are gone and there is no more honeydew on your tree, the sooty mold will disappear. Does this Spark an idea?
Instructions
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Apply an insecticide containing dormant horticultural oil in March to help kill eggs. Coat the foliage thoroughly to ensure you get as many eggs as possible. Always read the label and follow the manufacturer's directions when you use insecticides.
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Spray your tree with water periodically throughout the summer if the sooty mold is bothering you. You'll be able to wash off some of the mold and possibly some of the honeydew as well. Wet the leaves in the morning so they have time to dry before nightfall.
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Apply an insecticide spray containing bifenthrin, carbaryl, cyflulthrin, malathion or permethrin in late August or early in September. Make a second application 10 days later and thoroughly coat foliage. Late summer sprays target the nymph stage of scales before they have developed a protective coating.
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Tips & Warnings
Ladybugs eat scale insects. A late summer application of insecticides could kill off these natural predators. Use insecticidal soaps if you're concerned about harming ladybugs. They are less effective but safer for beneficial insects.
References
- Photo Credit Hemera Technologies/AbleStock.com/Getty Images
