I realize this topic is quite old, but I think it makes sense to glom onto it for my own purposes, which relate somewhat to the original post. Brian, I hope you were able to achieve more success with your Orange tree in the RBII container. Have you moved to the greenhouse yet, or is the tree still in container. I'd love to know what you did to (if anything) to improve the situation.
I have a small "grove" of citrus trees in containers, aging 3-7 years now. I planted the trees in three-quarter high 55-gal food-grade containers. Most are raised off the ground with large 2" holes drilled in the bottom. A few are on ground because they were so heavy I wasn't able to lift them enough to add "bricks" to raise them. I suppose those might also be rooting through the holes somewhat too now.
I've also been fertilizing with Osmocote Plus recently, and before I was using organic liquid fertilizers and foliar spays. The trees had a few good years, but I expect they are heavily root bound at this point. I do prune them yearly to keep them to a smaller size. I think the root bound condition causes them to drop a lot of fruit in the hot summers here when the water just passes through the roots and doesn't cling to the limited soil left in the containers.
The reason I'm posting today is that I've noticed in the new growth from after the pruning early Winter (maybe it was around Oct '17 the pruning took place); I'm noticing my Robertson Orange and a Eureka Lemon showing a lot of Yellow leaves. On the Robertson, the leaves are yellowing in some areas of the tree and perfectly green in others. It almost reminds me of the fusarium and verticilum conditions on an infected Tomato plant.
We've had a lot of rain the past month, so the soil has been fairly damp, but I believe it's still draining well. It's a mix of perlite, peat, redwood chips, some organics and more recently a top-off with coco hulls. I hit the trees with liquid iron and few weeks back. I don't think this is nutrient deficiency, but I can't say what it might be. Any thoughts on the cause?
Thanks!
Eureka Lemon:
Robertson Orange:
Full "Grove":