Burst of colors coming soon

Soon, the University of Delaware campus will be ablaze in color. The American elms on The Green will become a soft yellow, the maples at Trabant Student Center will turn crimson, the serviceberry trees at the Fred Rust Ice Arena will display orange leaves and the gingkos on South College Avenue will become a luminous, clear yellow.

“The fall landscape is spectacular on the University campus,” Susan Barton, Cooperative Extension horticulture specialist, said. “When it comes to fall foliage, I believe our campus and the entire Mid-Atlantic Region are every bit as beautiful as New England,” Barton said.

But, the next week to 10 days are critical in determining just how good the foliage will be this year. Weather conditions in mid- to late-September play a key role in fall leaf color, which typically peaks in Newark during the third week of October.

Current conditions are of prime importance because the process of leaf change gets under way at the time of the autumn equinox. During the summer growing season, leaves look green due to the presence of chlorophyll, which masks the other pigment colors. With the arrival of the autumn equinox and the start of longer nights and shorter days, chlorophyll production in the leaves slows, and soon other pigments become more visible.

Too much rain now, especially coupled with warm conditions, will make for less-than-brilliant color next month. But, if the rest of September brings sunny days and cool, crisp nights, more good things will follow, in the form of picture-perfect October foliage.

Barton explained that the purple and red pigments in the leaves need the breakdown of sugar that occurs on bright autumn days. Cool temperatures at night break down chlorophyll, allowing the yellows and oranges to show. However, too cool isn’t good, as an early frost kills the leaf cells and reduces the coloration process.

Summer weather also has an effect on foliage “wow factor.” Drought will cause premature leaf drop, sometimes as early as July. And, an excess of water—like Delaware has had this summer—also causes some early defoliation because of fungal diseases that attack the leaves.

A variety of other factors have an impact on foliage coloration, including plant genetics and soil conditions (such as the pH and the availability of trace minerals), Barton said.

The extended forecast for Newark is calling for sunny days and cool nights, so the October foliage should be impressive. But, Barton said she won’t get discouraged if it rains or nighttime temperatures warm up. “Even when the leaves aren’t at their best, they still put on a pretty good show here in the Mid-Atlantic,” Barton said. “I can’t wait to take a stroll around campus next month and enjoy the fall foliage.”

Article by Margo McDonough
Photo by Lane McLaughlin

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