Landowners across the state have reported post oak trees dying suddenly. After abundant rainfall fell in Texas this year, many are left confused and looking for answers.

The Texas Plant Diagnostic Center in College Station said calls started coming in around early spring and have continued throughout the summer. Plant pathologists at the lab realized there was a widespread problem and began to be alarmed after receiving calls this spring when post oaks should have been developing their green leaves.

The reports have come from urban, rangeland and woodland environments according to Sheila McBride, the lab’s lead diagnostician.

The leaves begin to yellow, develop spots and ultimately turn brown, but remain on the tree, McBride said. By the time the symptoms begin to appear, the tree is already dead.

McBride and Dr. David Appel, Texas A&M AgriLife Research forest pathologist in College Station, describe the phenomenon as rapid oak decline. But they say by the time someone notices the symptoms, the tree has been declining over a period of time.

“People will say the tree died overnight. But, actually, it has been developing these early symptoms for a long time before that. It collapses. It dies. It turns completely brown very quickly,” Appel told AgriLife Today.

The Post Oak Savannah Region of Texas, which is located between the Blackland Prairies and the Eastern Pineywoods, has seen significant post oak losses. This region extends from the Oklahoma border to south of San Antonio, according to the Texas A&M Forest Service.

Appel said there is a number of environmental factors that have contributed to the sudden decline. He said the drought of 2011 triggered the series of factors that have led to the phenomenon.

“So when we go through rapid environmental extremes from year to year that makes for a tough time on the post oak physiology,” Appel said.

Appel noted weather conditions like the wet spring followed by hot, dry weather also drove the decline in post oaks. Appel stressed that oak wilt is not the cause of this phenomenon. He said oak wilt targets primarily live oaks, not post oaks.

“We have a perfect storm of environmental conditions,” Appel said. “The tree’s physiology is weakened by the drought and weather extremes, and then we get what we call contributors—canker-causing pathogens, root rot pathogens and insect borers. We believe that is what’s really leading the problem with the post oaks.”

Post oak trees don’t like to have wet feet, so they should be allowed to dry out and stay dry.

Appel said urban tree owners can take additional measures to help slow the decline of post oak trees. Appel said don’t allow turf to grow to the base of the tree to avoid having to water it. He also said to try vertical mulching by drilling holes in the ground around the tree, and then fill the holes with organic matter. He said that allows the soil to dry out and encourages the growth of the roots in the immediate vicinity of these holes.

He said there are limited options for post oak trees in rural woodland areas.

“There’s really very little we can do about this. When you see these trees dying off, if it’s a forest management situation, we may suggest thinning of the stand because if you remove the weakened individuals, it may help the others have more available nutrients,” Appel said.

If a tree owner suspects a tree has died, Appel said the best thing for them to do is wait until next spring to see if the tree leafs out again.