Insects, disease, wet spring conspire to mute fall colors this year |

Insects, disease, wet spring conspire to mute fall colors this year

Janet Urquhart
The Aspen Times
Glenwood Springs, CO Colorado
Janet Urquhart The Aspen Times

Autumn leaf peeping in the mountains around Aspen may be as spotty as the leaves.

While the aspens in the gulch on Smuggler Mountain – the spot above town where the leaves are always first to turn – are already displaying the season’s first glimpse of gold, some aspen groves near the Maroon Bells have already dropped their leaves. And trees on Buttermilk also appear be losing their leaves before the fall colors commence.

Blame the wet spring, says city forester Chris Forman.

When the leaves of aspens and cottonwoods turn brown, crinkle up and fall off early, a fungus, Marssonina populi, is usually to blame, according to Forman. The fungus is always present, but gains strength with a lot of moisture, he said.

“It really thrives in wet conditions like we had this spring,” Foreman said. “I think that’s what’s going on. I haven’t seen a lot of it here in town yet, but I have seen it.”

The fungus isn’t typically detrimental to the overall health of the trees unless it recurs year after year, he added.

At Maroon Lake and the Maroon Bells, a popular spot to view the fall colors, some aspens are still holding healthy-looking, green leaves. In some groves, though, the leaves have already fallen and in others, the leaves are curling up and browning. Still other boast black spots.

Aphid damage can also lead to early browning out of aspen leaves, and Aspen had a memorable infestation of aphids early this summer. In addition, there were spider mites, which cause the tips of the leaves to turn dark and die.

“We had a lot of that in town earlier this year,” Forman said.

He is not, however, predicting a lackluster season of leaf peeping.

“I’m not going to blow the whistle on that one yet,” he said.

The peak of the fall colors in the Aspen area typically occurs in late September.

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