Could you post picture of the 2 trees and the fruit. Are these trees grafted or grown from seed. Are the trees of the same variety kumquat, EX Meiwa & Meiwa Nagami & Nagami.

If you have a Meiwa & a Nagami they will taste very different from one another.

If your trees are from seed, I would like to know your secret on seed grown kumquat trees.

Steve

If you are interested in seeing my seed grown meiwa kumquat click below & best of luck with your trees

Here is a link that might be useful: https://plus.google.com/photos/111099372377958308731/albums/5967653232333283409/5972084004664102114?banner=pwa&pid=5972084004664102114&oid=111099372377958308731

My kumquat

My kumquat

{{!gwi}}

Here is a close up of the fruit on the bad tree. They are both Nagami. They are grafted and I bought them from a nursery. They are both in separate pots and are on a south facing wall with eastern exposure.

I hope this works for the photos.

Here is a link that might be useful: photos of Kumquat trees Link

The kumquat tree to the left will get a lot more sunlight as the sun swings past mid day and the roof shades the more eastern tree. The tree to the left will get a lot more wind and requiring more water. If you are watering equally the tree to the right may have too much. This could cause a difference in the two. I noticed light discoloration in the leaves, but not enough to cry greening. Someone else will have to help you with this one.

Both trees are in black pots. This is generally a no-no as the pots heat up to much in the lower level winter sun.

Looks like it could be bloom rot not really sure but the fruit looks funny to me. The tree thats eatable does the fruit look heathy. Bloom rot is a fungus that you dont see until fruit rippens. And can sometimes effect taste of fruit Im not expert let a few others chime in first. If its bloom rot a fungside would fix it but not the taste of your fruit. Fruit would be safe to eat but not joyful to eat.