Here’s a description of the garden issue I found:
The following was sent to me from a close friend just a few days ago:
Can you tell me what might be causing my camellia to have such unhappy leaves? It is dropping unopened buds as well.. rust? Rot? Disease? Do I need to feed it? Move it? Its in a large pot on north side of house, gets a bit of early morning sun. Lots of new growth promising to come but these unhappy leaves have me concerned. Quite a few of the greener leaves have dark spots. –Misty H.
And here’s what I think is going on, with a reference from a site :edu website:
The yellowing of the leaves and the fact the writer states new growth is affected leads me to believe the soil ph is too high for this plant. Known as ph induced chlorosis. Camellias need a slightly acidic soil- between 5.0 -6.5ph. Soil acidification is necessary for optimum plant growth. Plants with yellowing of leaves may be suffering from iron deficiency- this happens when soil ph is higher than the plant can tolerate.
Soil acidity is improved by adding sulfur and or iron. It can be added to the soil or by foliar spray. Since this camellia is in a pot the easiest method would be to repot with an acid loving soil and to fertilize only with fertilizer for acid loving plants. (rhododendrons/azaleas/camellias). The suggestion for potted camellias is to repot every 3 years related to plant growth and the watering out of nutrients. Being in a pot increases it’s water requirements during the heat of the summer. Adding a slow release fertilizer and mulching may help to slow the leaching of nutrients and ph and drying out.
https://catalog.extension.oregonstate.edu/sites/catalog/files/project/pdf/ec1560.pdf
The following reference is in regard to potential fungus’, mildews and insects but does not address the actual yellowing of the leaves. Keeping in mind when a plant is stressed it can be a target for infestation.
http://hortsense.cahnrs.wsu.edu/Search/SearchByAlphaPlantName.aspx?letter=C&PlantDefId=7
Hope this is helpful.
Thank you for the well researched and helpful plant problem and solution!
Thanks Jennifer. Succinct, to the point, and accessible and understandable path for your friend to follow. Additional info on how plant may be weakened and vulnerable to other problems is useful context also. mm