Good morning Karil,

Thank you for your question.

Once established, baptisias are very tough plants. How long have they been in the ground?

This looks like a possible fungal or overwatering issue. Are the plants in sun or shade? How often have you been watering? Do the leaves feel soft and a little mushy on the black areas? Baptisias have a tap root and if the plants have been in the ground for awhile they will be drought resistant. Newer plants will need an occasional drink in summers like this.

If you’ve been watering heavily I would water less often & avoid getting the leaves wet. Also, is there mulch? If so, move it away from the base of the plant so there is space between the stems and mulch. Wood mulch against the base of the plant can create rot and other disease issues.

Before you water again, dig down about 4"-6" and grab a handful of soil. Squeeze it in your hand. No water should release when you squeeze it, it there is excess water, don't water. Check every 2 days until the soil feels like a squeezed out sponge, then give the plants a good soak. Wait the same number of days between waterings, unless it rains, then check it again before you water again. You want the soil to feel like a squeezed out sponge, not too wet and not too dry, between waterings.

Your plants should recover, they just need a little bit of time.

You can cut the black stems off, but do it when the weather is dry. This plant is tough, it should be fine next year.

Just to be safe, bag and remove all the stems and leaves from the baptisia after we have a freeze this fall.

You could also send a sample to the MSU Lab for confirmation. I’ve included the link for the lab & a couple others that you may find hepful.

https://www.canr.msu.edu/pestid/

https://www.canr.msu.edu/resources/sclerotinia-sclerotiorum

https://www.canr.msu.edu/news/scouting_for_diseases_septoria_leaf_spot

Good luck & have a great day!