Stewartia monadelpha is one of my favorite species. Hands down. But the past two years I have run into the same problem with my seedings. They are 3-4 year old seedlings growing under 40% shade in good bonsai soil(akadama pumice lava). I have had them analyzed by NC State and they came up with nothing. I stay on top of my fungicide applications so I’ve ruled that out. And I don’t think it’s bacterial. Leaves on lower branches start to curl at the tip of the lead then brown from the tip to the petiole and leaf drops. It then continues through the rest of the plant. Anybody have a clue. I can send pics if needed. Thanks
This is a species that dislikes transplanting and any forms of root disturbance. The symptoms you are describing could be attributed to root problems of some kind interfering with water intake. Other key factors are intense periods of heat or too much sun. You mentioned the shade cloth but not your location or any other factors that may play a part. They do prefer a more acidic PH to the soil, so water quality could be an issue as well. Generally the rule of thumb is to keep them damp but not to wet. I would focus on more shade, consistent moisture and very careful transplanting techniques. Deeper containers may also make a differrence with more consistent moisture and temperatures.
I have had similar issues with members of the camellia family and solved them by implementing the above care practices. Of note i use a higher percentage of Akadama for these trees it helps with moisture retention.
Sounds like a water/root issue to me too. What’s the pH of the water the seedlings are getting?
Thanks Frank and Jonas. I’ll try a bit more shade when it gets to be the hottest time of year. It’s strange that it has happened in August for two years running. I’ll check the ph again. It was running 6.6-6.7 early season. Maybe it’s too alkaline for the Stewartias. I don’t think it’s a root problem as I’m growing them in bonsai soil. And I don’t allow them to dry out to much. It’s been a discouraging journey at times with Stewartia monadelpha and I almost gave up on them last year. Truly this is one of my favorite species. Such an elegant tree. Thank you again
If your PH is in the high 6’s that shouldn’t be the problem. Do you have any idea of the mineral content (TDS?) of your water? My deciduous trees tend to show a lot of stress this time of year because the mineral build up in the leaves becomes too much. In my experience Stewartia in particular tend to be very susceptible to this and I gave up growing them because of it.
Many thanks Danny. I truly appreciate your advice as I ltry love Stewartia monadelpha and I want to figure them out. My ph was reading about 6.6 so I’m good on that. We run off of well water and it’s considered hard because it does leave mineral stains inside our showers and toilets after a few years. It doesn’t seem to affect my tridents or Japanese maples and not all of my S. monadelphas. Thank you again for trying to help me connect the dots on this problem
I can also say that it’s pretty common for stewartia to look pretty beat up this time of year. I’d find it concerning if the leaves are turning in spring, but not so much if they’re dropping now and recovering the following spring.
I hope you’re right Jonas. It has been frustrating not being able to figure out a plant I love so much. Thank you for your help