How should I treat the yellow dots on my Turtlehead plant?


There are yellow dots on the leaves of my Turtlehead plant. I sprayed neem oil solution but not sure if that will prevent more from spreading. Should I prune infected leaves?


Jonathan Foster, Home Horticulture Outreach Professional

I’m sorry to say I don’t immediately recognize these spots, nor did a quick bit of research turn up any likely candidates. There are a number of bacterial and fungal pathogens that can cause leaf spots in garden plants, but without lab analysis I’m unable to diagnose them. So I’m going to recommend submitting the photo (and any others you have, including a whole plant shot to show the extent) to the UMaine Plant Disease Diagnostic Lab. There is a small fee associated with their service, but you’ll get a confirmed diagnosis and recommendations for treatment. I wouldn’t advise using any more neem oil until you have a firmer idea what’s going on.

In the meanwhile, I would pursue best cultural practices for managing leaf spotting: prune out the infected areas (as you suggested, and keeping samples if you want to submit them to the lab), thin any plants that look overgrown or tangled, concentrate supplemental watering to the soil below the plant and not “overhead” watering, and remove any dead plant debris from the soil underneath the chelone. You are basically pushing back on the warm, moist, still air conditions that promote these infections, improving air movement through the plant, and mitigating excessive moisture on the foliage. The lab may have additional suggestions, but these are all good cultural approaches in the garden, so they won’t hurt.

Apologies for not being able to give a firm answer, but I wish you happy gardening, nonetheless.