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Looking for thoughts on what to spray on phlox leaves? Elderberry bush/tree also looks like powdery mildew. What can I use on that as well? #876663
Asked July 10, 2024, 12:29 PM EDT
Looking for help on what to do on plants. It looks like a Powdery Mildew??
Leelanau County Michigan
Expert Response
Yes, that looks like powdery mildew. The weather this year has been conducive to powdery mildew. Some species of plants and then specific cultivars of those species are more or less susceptible to powdery mildew.
The first image is not elderberry. Is it an Amelanchier or service berry? The fruit is showing that it has a rust fungus. Here is information from Minnesota on rusts that impact plants in the rose family (which includes service berry). It also appears to have mildew.
Mildew is hard to control once it is well established on the plant. Preventative measures should be taken with the hopes of it not getting established. Mildews thrive in stagnant, humid weather. Make sure your plants, especially phlox, are in full sun. It should have good airflow around the plant (not crowded). You might want to divide your large clump this fall so that nect year it has more airflow. Make sure you clean up the leaves and cut down the plants in fall and remove the debris from your garden. The fungus can stick around in debris, so you want them away from your plant.
Here is a link to information from Iowa State.