Nugget of Knowledge: Fall colors

Longer and cooler nights trigger color transformation

Nugget of Knowledge

YOUNGSTOWN, Ohio (WYTV) – Between October 8 and October 16, we’ll have the peak of the fall colors here in the Valley.

Once the leaves develop in the spring, they get a constant supply of chlorophyll, which gives them their healthy green color.

So what causes the leaves to change color?

The purpose of the leaf is to create carbohydrates which the tree will use to grow the following season.

Once the nights grow longer and cooler, a change occurs. Where the leaf meets the stem, cells start to divide and that clogs up the artery to the leaf. This is called the abscission layer.

This cuts off chlorophyll, causing the leaf to turn from green, to orange, red or purple. This also cuts off the water supply to the leaf — a reason they dry out, curl up and crunch under our feet.

As far as ideal conditions, a drought — which we’ve had in August and September — causes the abscission layer to form early, causing leaves to fall before turning colors.

Since we haven’t had a good frost, expect to see some reds and purples. The best weather for vibrant colors is a wet growing season, followed by a dry autumn with cool overnight temperatures, so this will not be the most favorable year for peak colors.

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