Being driven through New York State recently it was noticeable that pockets of early fall leaf colour were appearing. Stopping to investigate what was causing some trees to change colour earlier than others, we discovered that water was the main contributory factor.
The leaves shown in this image belong to trees growing in a bog. Wet Springs and sunny Summers are regarded as the best weather conditions for generating Autumnal leaf colour as this leads to greater quantities of sugar being produced in the leaves.
We have noted that on schemes where irrigation has been installed trees benefitting from increased water are producing more impressive end of year colour displays than others struggling without additional water.