What's wrong with my Baptisia? - Ask Extension
First there were holes in the base of the leaves, and now there are black spots on the leaves. What should I do? It was planted last July.
Knowledgebase
What's wrong with my Baptisia? #751084
Asked May 20, 2021, 1:53 PM EDT
First there were holes in the base of the leaves, and now there are black spots on the leaves. What should I do? It was planted last July.
Olmsted County Minnesota
Expert Response
Hi,
The hole in the stem may be the indigo stem borer. Look for the caterpillars and you can treat with Bt. The black spots on the leaves are probably from humidity and water on leaves. Water at ground level.
https://www.insectidentification.org/insect-description.php?identification=Indigo-Stem-Borer-Moth
Thanks. What is Bt?
Is it OK if I just remove the caterpillars?
Sure, you just remove them. Bt (available at garden centers) is a bacteria that is lethal only to caterpillars and does not affect pollinators. http://npic.orst.edu/ingred/bt.html
Thank you!
You’re welcome!