If you’re wondering if the damage done by this summer’s invasive caterpillar outbreak will affect fall colors, you’re not alone. The answer is—hardly at all!
A healthy, leaf-bearing tree that was defoliated by caterpillars should have already grown new leaves again, though these leaves may be smaller than normal. However, fall colors are determined by environmental conditions rather than leaf conditions. In autumn, the best conditions for vibrant fall colors are dry, bright days with cool, frost-free nights. Weaker fall colors are caused by early frost or lots of rain. Rainy weather can leach water-soluble anthocyanins (which are responsible for the range of red colors) from leaves and have an overall dampening effect on fiery colors.
Want to know more about the science of leaf change? Check out last year's Facebook Live on fall colors, or visit the US Forest Service website.