Why are Some Kumquat Branches Leafless?

Q. I have a Kumquat citrus in the ground for 8 years. During the last 2 years a lot of leaves fell off in the Fall leaving some branches leafless. Yet some branches stayed green with new shoots coming out. What might be the cause of the problem?

A. Its very helpful when pictures are included with the comments. Sometimes pictures change everything!

The tree, from the pictures you sent, looks dense and full, with a few “blind” shoots here and there. The tree might be too dense. Leaves need sunlight and produce a net energy for the tree to stay productive and healthy. Rather than leaves producing energy for the tree, leaves growing in total shade will be dropped from tree limbs because the tree must exp  

end energy to keep them.

Open the Canopy by Pruning

            I would open the tree canopy to admit light to the inside. This will encourage fruit to develop throughout the canopy rather than just at its edges where there is light. Do this by total limb removal; “thinning” cuts. Prune so that limbs are four to six inches apart, not growing on top of each other.

Look at the Ground

            A trick to know if there is enough light penetrating the canopy is to look at the tree’s shadow on the ground at noon during midsummer. The shadow created by the canopy should have speckled light throughout it. If an area of the shadow is totally dark, then this is the area of the tree that needs to be pruned to admit more light. Admitting more light allows better fruit production throughout the tree canopy and removing a few limbs here and there during the summer does not hurt the tree.

A dense shadow on the ground under the tree at noon during the summer indicates no light is entering the canopy to cause fruit buds to form. Time to do some light summer pruning!

            Otherwise you might be giving the tree water and fertilizer, particularly nitrogen, too often.  Water when the soil moisture is starting to dry. On a soil moisture meter this would be an average of “5” on a ten-point scale at a depth of about 4 to 6 inches and measured in three different locations.  

This moisture meter does not have its tip in the ground so it is reading the dry air at zero.

Never water daily. Apply water to at least half the area under the tree canopy and apply enough water to get it 18 inches deep.