Last year, I have heavy loads of Indio Mandarinquat fruits in my multi-grafted FrankenQuat (all kumquat families and hybrids that I have collected and grafted). I left a few of them on the tree and did not touch them. They were brightly orange colored, November of last year when I left them alone. Come spring time, these turned to yellow green and come summer time, they turned green. Now they're starting to turn orange again, more than one year on the tree! I sampled every three months, so have tasted 4 fruits by now and found that the juiciness did not vary much. The flesh turned sour as the flesh turned greener. The rind also becomes astringent and gamy through time. Perhaps late December, I'll taste them again. The fruit size seemed to be the same, but now slightly larger than the new batches of fruits.

Has anyone observed these reverting back to green from orange and then from green back to orange again. It is amazing that the fruits stayed for more than 18 months since they were first formed.

Joe, regreening is really quite common, in many citrus varieties, especially Valencia, and other citrus fruits that have the ability to remain on the tree for extended periods. The reason Valencia has such a problem with re-greening, is that the Valencia fruit can hang on the tree for a very long time, even into the second summer. In the spring, as citrus trees begin to grow, they produce large quantities of chlorophyll, which is the green pigment in the leaves and fruit. As the chlorophyll shoots up to the new growth, the skin of the ripe fruit also absorbs a little, giving it a dose of green. Typically, regreening only occurs around the stem end of the fruit, but can re-green the entire fruit. Despite its greenish skin, the fruit is still fully ripe on the inside. Why cirus regreen is not fully understood. There are years in which regreening is a problem across the industry and years in which it is a minor concern. This variability strongly suggests that climate is an important governing factor. While the grower can do little to change the climate, some research has shown that nitrogen management can be used to moderate the affect of climate. The quantity of fertilizer nitrogen applied and when and how it is applied all affect regreening. Generally, the higher the nitrogen fertilization rate, the greater is the risk of regreening. If I remember correctly, you use Ammonium Sulfate 21%N to fertilize your trees. - Millet

Yes, but only when I want to push growth, I would apply ammonium sulfate. I usually use 6-10-20 with minors and add ammonium sulfate plus other what's on-sale supplements and minors to come close to 3-1-3 ratio for fruit production. Potted ones receive the 5-1-3 ratio. I have some regreening on my Valencias, but those quickly turned to orange when nights dipped below 45 deg F. I didn't expect these on the Indio Mandarinquats as the regular kumquats and calamondins would usually dry up on the tree if they don't fall off.

pictures below

changshou kumquat

indio mandarinquat