The oranges on my tree have always been nice, large, orange and juicy. This year there is a nice amount of them on the tree, they are what I would consider full size but the peak is completely green. Inside they appear to be ripe since they are very juicy, but they are sour. I would even tend to say they are on the over ripe end due to the bottom of them starting to split a bit. The tree sits next to a lime tree. Any chance they could have cross pollinated? Even if the trees have both been there for years.
Ventura County California
The splitting of some of your oranges should not be taken as an indicator of maturity. Fruit split is a stress response to soil moisture fluctuations. The maturity/ripening of citrus has two major factors: decreased acidity and increased sugar content. While peel color often does not happen at the same time (i.e, green citrus may be mature internally), the sourness (acidity) that you are experiencing indicates that they are not fully mature. With additional time on the tree, the acidity should decline further and the sugar will increase. Citrus fruit store on the tree well, provided the tree is not experiencing drought conditions. The longer you can let them stay on the tree, the better they should get in eating quality---and color should come along in a few weeks too.
Thank you so much for your quick and thorough reply. I hope you know what a huge service you are providing to those of us not at all knowledgeable about the intricacies of plant life. I appreciate your assistance.