Sunny days, cool nights enhance fall colors

What causes our leaves to turn color in the fall? I love this time of year. Our autumn colors are nearly as good as those in New England.

— Don J., Medford

The leaf lovers here at SYA concur with your assessment of our leaves, Don.

In fact, it is hard to get any work out of them when the leaves are at their brightest each autumn, what with their adoring gazes at the horse chestnuts in our parking lot.

But we were able to get one to walk away from the window long enough to observe that they — the leaves, that is — turn red out of sheer embarrassment.

Sorry, that was a really bad autumn joke, one whose poor taste demands we fire the jokester. We will do that, just as soon as we get someone to own up to it.

Meanwhile, serious plant scientists say the reduced sunlight and colder temperatures force the trees to store more energy and stop producing green chlorophyll. The latter is produced during the photosynthesis which occurs during spring and summer.

The colors are different for each fall foliage, depending on temperatures, they report. The best colors occur when there are dry, sunny days with cool but not freezing nights. That brings out the incredible colors of reds, yellows and orange.

Freezing temperatures can cause the leaves to drop suddenly, causing us to miss their beautiful transition.

Meanwhile, one of our favorite fall foliages is poison oak with its reddish-pink glow. But we recommend you appreciate it only from a distance.

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