Blue and gold aren’t the only colors at the University of Delaware. This time of year, the campus is ablaze in fall foliage. The American elms on The Green become a soft yellow, the maples at Trabant Student Center turn crimson, the serviceberry trees at the Fred Rust Ice Arena display orange leaves and the gingkos on South College Avenue become a luminous, clear yellow.
“The fall landscape is spectacular on the campus,” says Susan Barton, UD Cooperative Extension‘s specialist for ornamental horticulture. “When it comes to autumn color, I believe the campus and the entire state are every bit as beautiful as other regions I’ve traveled to during the fall foliage period.”
This week — the third week of October — tends to be the peak time for foliage in Delaware. The summer’s intense heat and drought conditions shouldn’t significantly impact the “wow factor” of the foliage, according to Barton.
“During the heat wave, some trees experienced leaf drop or brown, withered leaves and they obviously won’t be looking good this fall. But for the majority of the trees that didn’t suffer from heat it was actually mid-September to mid-October that was critical in determining the quality of the foliage now,” says Barton.
The process of leaf change gets under way at the time of the autumn equinox, she says. 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.
Sunny days and cool nights around the time of the equinox deliver the most dramatic fall color.
Purple and red pigments in the leaves need the breakdown of sugar that occurs on bright autumn days, explains Barton. 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.
Too much rain in late September and early October, especially coupled with warm conditions, can make for less-than-brilliant color at foliage time. Delaware received a lot of rain in a short period earlier in the month – 7 inches was recorded in Newark on Oct. 1 – but that shouldn’t impact the foliage.
“That rain wasn’t that unusual — except for one day — it was just concentrated after a long period without rain,” says Barton. “If you counted up all the rainy days in the fall, we haven’t had that many yet.”
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), she says.
Barton gets to enjoy great fall color not only during her workday at UD but also at her 7-acre property, where she’s planted many natives that are known for fall color. Some of her favorites are sourwood, which turns brilliant red, and fothergilla, a shrub that has multi-colored leaves.
“Out of all the fall colors and hues, orange is my favorite,” she says. “I love orange sassafras, serviceberry and sugar maple. Even better, though, are sweet gum trees because they have orange color plus yellow and purple, all on the same tree.”
Barton has planted serviceberry behind a low retaining wall at her home and is looking forward to enjoying its bright orange display. But she’ll need to drink in the view quickly – serviceberry only stays orange for a few days before dropping its leaves.
Most native American plants are speedier than their European counterparts at transitioning from fall to winter, she says.
“In Edgar Anderson’s book Plants, Man and Life he notes that our native flora evolved for our ‘violent American climate,’” says Barton. “He describes it as ‘going into the winter condition with a bang.’”
Sounds like it’s time to get outside before the fall fireworks are over.
Article by Margo McDonough
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