Dear Sarah,

Thank you for contacting us about your camellia. There are a number of possible causes for yellowing leaves including, nutritional deficiencies, weather conditions, and root rot. A photo of the leaves might reveal some clues, however, a soil test is usually recommended. 

If the yellowing appears only on one plant and does not affect any other nearby, please send a couple of photos both close up and of the entire bush/tree including the root zone. If it is possible, we can try to make some suggestions. 

Hi - I will try to send some pictures. Can I get a soil test done through your extension on Capitol Street?

Hi Sarah,

Thanks for sending the photos. I've consulted with my colleague and we think the best approach would be to wait a few weeks and see what happens. Chlorosis (yellowing leaves) can be caused by several things including weather; however, I'm not aware of any fungal infections that would cause it. 

I suggest you follow the instructions on the fertilizer and apply it as specified. Wet weather can cause a temporary reduction in nitrogen levels, and that may be the problem.

OSU Extension does not provide soil tests but the following links will tell you how to take samples and find a laboratory to do the testing. Be sure to tell them the kinds of plants you are growing (vegetables, shrubs, etc.) They should be able to tell you if there are any deficiencies and how to correct them. It's good to do a laboratory test once every 5 or 6 years to establish a baseline for any further fertilizing or amendments. 
https://www.simplysoiltesting.com/
https://catalog.extension.oregonstate.edu/ec628
https://catalog.extension.oregonstate.edu/em8677
https://catalog.extension.oregonstate.edu/ec1478

I hope this information is helpful. Please write again if you have any gardening questions or if you notice a change in your camellia.

Very much appreciated! It has not appeared to change dramatically in the past week, so I think this is pretty solid advice