Mounding on Plox flowers

Asked July 7, 2019, 3:09 PM EDT

Is there a home solution (vinegar ,etc.) to this problem?

Marion County Oregon powdery mildew flowers: annuals and herbaceous perennials

1 Response

It looks like it is powdery mildew affecting your phlox. Apparently it is a common problem with phlox and we have had the perfect weather for it this year. Oregon State plant disease handbook has a page on Phlox Powdery Mildew which lists cultural practices that can reduce disease pressure as well as chemical controls. Look for sprays with a small “o” for organic, or an “h” for homeowner. These chemicals are available for homeowners to purchase. When using a chemical, read the entire label then follow the directions.

Iowa State University Extension also has a page on Powdery Mildew of Phlox with more information regarding prevention of the mildew.

Hope you find these resources useful in your campaign for beautiful phlox.