Trees weakened by drought, flood are falling victim to deadly fungus

Half of park’s oaks lost; more species have been infected

Since 2011, the Army Corps of Engineers has battled area floods, drought and now hypoxylon fungus.

Millwood State Park has lost 50 percent of the oak trees, and about 40 percent of other trees such as elm and hickory have been infected by a fungus known as hypoxylon canker. Hypoxylon canker attacks oak and other hardwood trees.

Drought and floods take their toll on trees slowly, said Roy Burk, a forester with the Corps of Engineers. The disease spreads when trees are stressed, and periods of flood and drought have created those conditions, he said. Burk has worked 33 years as a forester.

“The fungus lives in the bark of oak and rarely affects the trees until severe stress,” Burk said.

When the fungus surfaces, there’s an almost 100 percent chance the tree will die, he said.

By the time the spores become visible, the tree is dead. Once the fungus invades the tree, the sapwood decays rapidly. Dark decay lines can be seen running through the wood. Trees that have died from hypoxylon canker and are in an area where they could fall on structures, roads, fences and power lines should be removed as soon as possible, according to a Texas A&M Forest Service report.

“We’re working with loggers trying to salvage the trees. If it’s decent wood, the majority will be sold as pulp wood,” he said.

“We’ve lost 75-year-old trees in the state park. The older the trees, the more susceptible to stress. But we’ve seen 6-yearold trees get it and die. The trees were battling the drought in the last five to six years, and then we had the high-water events,” Burk said.

“The drought, floods and the fungus have been changing the dynamics of the forest,” he said. “So many species depend on acorns. It affects the habitat of the squirrels, deer and turkeys. Without acorns, the animals move to where there is food.”

The changes in nature also cause soil erosion.

“Losing the trees along creeks also causes the roots to die, leaving a void, which increases soil erosion. Then the tree falls into the stream and changes the flow of water into the lake. That’s why engineers don’t like trees on levees,” Burk said.

Battling nature is an ongoing process, he said.

“Mother Nature is doing its thing and it’s not just oaks. The high water devastated the hickories and almost wiped out the elm trees,” Burk said.

As the floodwaters dry out, the corps and loggers will cut the decayed trees, and the corps will replant trees.

Damaged trees in the state park will be removed to protect campers.

“If it’s come down to save the trees or save lives, the corps will save lives to avoid risking injuries if a diseased or damage tree looks like it might fall,” Burk said.

The corps is working with the state park crew on a dayto-day basis if trees need to be removed, and they will continue to monitor the trees.

“The guys have done a phenomenal job to clean up the park,” said Laurie Driver, spokeswoman for the Corps of Engineers.

The agencies will also work together to replant trees in the park, she said.

“Sometimes, we don’t understand how Mother Nature works. (She) is smarter than us, and we have to learn how to go with the flow,” Driver said.

“In other parts of the state, we have beetles attacking trees. There is always something,” she said.