Bee Balm With Powdery Mildew

What is your question for a Master Gardener?

This question was submitted by Sherry and answered by Advanced Master Gardener Bruce.

I have a three year old patch of bee balm. Gorgeous and seemingly happy , healthy, and spreading more each year and then mid June comes the powdery mildew. Now it is looking spindly, blooms and the petals just fall off immediately. In the past I have removed the stalks that show the powdery mildew and the plant just doesn’t do well. Should I pull this entire plant? Destroy it away from any other plants? treat the soil?

I would love to save it but I am not confident that will happen.I adore the plant and want to plant more next year – any recommendations? My location is Hancock County and I have attached a picture of the plant.

One more quick question – is it ever too late in the summer to plant new perennials?

Thank you and look forward to your response.

Bee Balm with powdery mildew spots

Thanks for contacting us Sherry with your question concerning powdery mildew on Monarda (bee balm). Unfortunately there is little that can be done in controlling or eliminating powdery mildew from plants.  Lower humidity helps in the control of mildew but we both know that’s not going to happen in Indiana.  The other suggestions are making sure it is in full sun and/or thinning out the stand of Monarda to help with air circulation which will slow the infection of powdery mildew.  If you thin out the plants, that will affect the impact of the color mass produced by Monarda?  I have added a link explaining powdery mildew.

To enjoy the mass of color provided by Monarda, you might want to consider investing in mildew resistant varieties of Monarda. I have included a link with a list of mildew resistant cultivars in case you decide to change.

It’s really never to late to plant perennials.  I shop season ending clearance sales all the time and don’t have problems planting them in late October.  The only exception is the 4″ squares of perennials. I only have about a 30% success rate of them coming up in the spring. In the future, I will stick the plant with the pot in the ground to overwinter.  If it comes up in the spring, I will take it out of the pot and replant it. If you have any questions, don’t hesitate to write back.  Good luck with growing!

https://web.extension.illinois.edu/hortanswers/plantdetail.cfm?PlantID=735&PlantTypeID=2

https://www.purdue.edu/hla/sites/yardandgarden/decrease-powdery-mildew-through-prevention/

Bruce