A drought-plagued summer probably will mean an early change of leaf colors this autumn, but the rains of August will spare the nation from a drab showing, a forestry professor predicts.

Steve Pallardy, associate professor of forestry, said he expects the fall leaf colors to rate a B-minus."We had very poor early growing conditions, and that's going to accelerate the appearance of color," he said. "If everything else is normal from here on, expect early colors."

The best ingredients for a colorful autumn include a mild, late-season drought and sunny days with cool but not freezing night temperatures, said Pallardy. Cloudy weather, continuous rainfall and a lot of frost can ruin colors.

Pallardy reports that leaves in northern Wisconsin already are turning and likely will peak around mid- to late September, about the same time in northern New England. Middle America then would reach its top coloration about a month later, he says.

Yellow leaves like those found on walnut and poplar trees are least affected by dry weather, the professor said. The yellow pigment is present in the leaves throughout the growing season but appears only as production of chlorophyll shuts down and the existing green pigments are destroyed.

The reds and oranges seen in sumacs, sweet guns and some maples form later and are affected by temperature, light and water supply.