Fall Color & Sour Tangerines

Question:

I have two Flowering Pears, Pyrus calleryana, planted on the same day exactly three years ago. One turns color in late October, while the other is just turning color now. Why don't they color up at the same time?

Answer:

  • Pyrus calleryana is a deciduous ornamental flowering tree with fabulous fall color. Whitehouse, Bradford, Aristocrat, Redspire, and Capital are some of the varieties available today.
    • Bradford Pear was the first introduction but has lost its appeal because the branches tended to split as they mature. Also, they're labeled as invasive in many areas because of their suckering. Flowering Pear was first introduced and bred to create a Fireblight resistant variety. Unfortunately, this never materialized as they are also susceptible to the disease.
    •  They're typically pyramidal trees with vertical branching and rapid growth, tolerant of dryness and pollution. They produce beautiful white flowers, deep green summer foliage in the spring, and red or maroon to purple fall color. The white flowers completely covered the trees in late February or March, resembling a huge white powder puff.
  • There are two possible answers to your question. One could be their different varieties which I don't think is the case because you didn't mention their names.
  • The other has to do with how they were propagated. Plant genetics dictates the timing of when the leaves turn color, along with many other characteristics.
    • The dominant green pigment in growing plants is produced by chlorophyll. The different leaf colors are only apparent when plants stop growing.
    • Those started from seeds are unpredictable, while cuttings mirror their mother plant. So, it's very possible your trees came from trees with different coloring periods although the same variety.
  •  The time period when the leaves turn color in the Chinese Pistache tree is between four to five weeks; however, it's much broader with a Flowering Pear. It's not unusual to see an individual tree in a row of Flowering Pears show color starting in late August, with the rest progressing through mid-December.
    • Also, there is no way to tell whether it will color up early mid-season or late ahead of time.

Question:

Answer:

I have a dwarf tangerine tree and a little lemon tree next to it that produces about ten lemons a year. However, behind this little lemon tree, there's a tall lemon tree that we didn't plant but produces large lemons (the size of grapefruit) with thick skins. Would the little lemon tree have more if we cut down the tall tree? Also, do you think lemon trees close to a tangerine tree make the tangerine tart and sour?