Is it still Summer? Leave me Hanging.

Why do leaves turn colour in the autumn? Is it the cooler nights, the date on the calendar or what?

While some may think it is the cooler weather or just the changing seasons, it's really the "photoperiod."

The photoperiod is considered to be the environmental trigger that causes fall leaf colouring, senescence and leaf drop. The pigment phytochrome senses the photoperiod. Photoperiod is often thought to be the length of the daylight period.

In actuality it is not the length of the daylight time, but the length of the night.

 

Here in these photos, we can see a situation where a section of this tree have not received the longer nights needed to trigger fall colouring. The leaves of this maple that are near the street lamp have been fooled into believing that it is still summer. The light from the street lamp shining on these leaves has led them to think that the longer days and shorter nights of summer have not gone away.

Plants that respond to photoperiodism, do not measure the length of the daylight but rather the length of the dark period. For these maple leaves, their night has been shortened by the rays of the street lamp. I'm sure at some point they will respond as the rest of the tree has done. My speculation is that the other leaves will create enough of the hormones that trigger the autumn responses to eventually cause all the leaves to colour and fall.

If you have a lawn/tree/shrub that needs some Tender Loving Care- get The KING OF GREEN, the King of Lawn Care:

Turf King Home

Click here to Request a Quote Online -

or call us at 905.318.6677 or 1.888.TURFKING (887.3546)

If you would like more information, please Contact us

Follow us on Twitter  http://twitter.com/turfkingofgreen

Join our Facebook page  

http://www.bit.ly/FacebookTK

Copyright 2009 Turf King-Hamilton. All Rights Reserved.