COLUMBIA — Fall's brew of wet weather, short sunny days and long cool nights has launched autumn's array of reddish-purple and yellow-orange foliage, according to the Missouri Department of Conservation.
The fall display will peak around Oct. 15 and continue into the fourth week of the month, said Dave Niebruegge, private land conservationist for the department. He said Missouri has more optimal conditions this year than previous years.
Moist weather is most important, "which we've had, no doubt," Niebruegge said.
He said leaves of the sumac and sassafras variety were the first to change color to a blazing red. Stretches of cool sunny days with 40- to 60-degree weather promote their colorings, said MU forestry professor Steve Pallardy.
Niebruegge said that while larger hardwoods such as oaks and hickories are still approaching color changes, Missouri’s smaller roadside hardwoods, like the sumac or sassafras, have been “turning good color for the last few weeks.”
Pallardy said hickory, elm and green ash will add dashes of yellow to the fall foliage.
Pin oaks, which line MU's Francis Quadrangle, are predicted to change color within the next week along with the rest of the oak varieties, Niebruegge said.
Pallardy said their leaves will turn more red than yellow if they receive more sunlight.
He said oak foliage in shaded areas will feature a yellow tint.
"A leaf closely shading another will create enough shade to cause the bottom leaf to have a yellow outline of the leaf above," Pallardy said.
Niebruegge said oaks stressed over the summer by jumping oak gall, which are very small bumps, or galls, left by insects feeding on leaf matter, will have less vibrant colorings. He added that white oaks in particular are affected by this phenomenon.
Pallardy said heavy frost will also cause the leaves to die and turn brown, bypassing the color change process.
The show, though hard to predict, is expected to last until Nov. 1, Niebruegge said.