The leaves are leaving, but not before a brilliant, Technicolor explosion of color! Why do leaves even change color? As the days get shorter in the fall, there is less sunlight for photosynthesis. Plants convert carbon dioxide in the air into sugars (glucose and starch) and oxygen by using energy from the sun through the process of photosynthesis. Chlorophyll is the green pigment necessary for photosynthesis. A decrease in photosynthesis that comes with less daylight means trees stop producing chlorophyll. As the green pigment fades over time other pigments present in the leaf are revealed, producing a veritable explosion of dazzling colors of rust, lemon and purple, a festival of color for professional leaf-peepers angling to get the “money shot”.
Weather plays a role. High quality foliage, a product of a warm, humid summer, will produce brilliant colors when exposed to sunny, cool fall days. A light frost can have a positive impact, but hard freezes can ruin the display. Cool, wet summers can cause premature displays of color. Our drought will probably mute colors somewhat, and extended warmth into September is delaying peak color by a week or two in many communities.
Temperature, light, and water supply all have an influence on the intensity and duration of fall color. Nighttime lows above freezing favor anthocyanin formation, producing bright reds in sugar maples. But an early frost will weaken the brilliant red color. Rainy, gray days tend to increase the intensity of fall colors. A hot, dry summer may take the edge off the color a bit this year, but the forecast still calls for an impressive display. Good luck out there!