Foresters with the Missouri Department of Conservation (MDC) report that many trees already have shed some or all of their leaves in response to this year’s historic drought. However, they say it isn’t too late for trees that still have live leaves to develop the vivid hues that make Show-Me State forests a visual feast in autumn.
Leaves turn colors when two things happen. First, sugars produced by photosynthesis are trapped inside leaves by chilly – but not freezing – autumn nights. Those sugars are the building blocks for red, yellow, orange, and purple pigments. Cool nights simultaneously cause the breakdown of green pigments, allowing other colors to show through.
The water trees need for photosynthesis was missing until recently, but this week’s rainfall came just in time for one last gasp of sugar-making. Given a few sunny days and cool nights, trees can still put on their autumn finery.
Fall color typically develops first in northern Missouri in early October and spreads south during the following weeks. The peak of fall color statewide usually occurs around mid-October. Foresters say the best colors likely will be seen little earlier this year, due to drought stress on trees.
MDC collects fall-color reports from foresters around the state and assembles them into a weekly report at mdc.mo.gov/node/4548.
By Jim Low, Mo Dept. Conservation