When the bough breaks

Bri Saseen was on her way to work one day last week when, seemingly out of nowhere, a giant tree branch came crashing down onto The Esplanade in front of her. “Fortunately everyone was going slow enough and we were able to stop,” she said. “But it was definitely scary—it covered more than one full lane.”

Luckily for Saseen and the other drivers on the road that day, the limb didn’t strike any vehicles. But, driving up and down The Esplanade, it’s clear that isn’t the only time recently a large branch has broken loose.

Apparently, limbs falling is a natural occurrence this time of year. A mysterious phenomenon called “sudden limb drop,” which occurs when the heat rolls in, causes branches to break, explained Dan Efseaff, Chico’s Park and Natural Resources manager.

“In the hot weather, trees start using more water and then if there isn’t any breeze the limbs will get heavy,” he said of one theory behind sudden limb drop. “It occurs every year in Chico.”

This year, however, in the fourth year of drought—and two years after the city of Chico eliminated its tree crew—the situation could be worse than normal. One way to help avoid sudden limb drop (also known as summer limb drop) is to prune trees. That’s something the tree crew did as regular maintenance on the urban forest, but that program has been suspended for the past two years. Instead, the city’s focus has been reactionary—fixing problems as they become known, using the services of local contractors—rather than proactive.

“We’ve been in low-maintenance mode for the last couple years,” Efseaff acknowledged. “We can get by [that way] for a little while, but there will be issues we need to address.”

He said the city has contracted out for some pruning—a crew was out the past few weeks trimming the trees in and around the parking lot at Second and Wall streets, where the Saturday farmers’ market is held, for example. He’s also in the midst of compiling the results of a survey on the health of the urban forest conducted in November. He plans to present his findings, along with a projected cost analysis, to the Bidwell Park and Playground Commission later this month.

Drought conditions are making the need to care for our trees even more important, Efseaff said. And the problem isn’t limited to municipal trees—it’s particularly true with current restrictions on watering and the movement to let lawns go brown.

“I have seen many trees decline in our area from the drought,” said Marc Wesley, co-owner and arborist for M&S Wesley Tree Service in Chico. “Soils have salts that usually leach down further into the soil, [and] when there is a lack of rain the salts start coming back upward and have negative effects on trees.”

In addition to losing nutrients, Wesley said without sufficient water in the soil, root systems will move toward the surface. “Roots will always take the path of least resistance. This is not good [because] as we are letting our lawns die, our trees have been forgotten about.”

To protect our trees during a drought, Wesley and Efseaff both recommend pruning as well as watering trees “deep,” meaning thoroughly soaking the area around the roots.

“Install a good drip system around the root zone of the trees, place mulch over the top of the drip line—this will help moderate the temperature of the soils, hold water moisture longer and provide the soil with beneficial nutrients for the trees,” Wesley wrote in an email. “Water the trees on a schedule and water deep (longer)—this will encourage roots to grow downward and help them become more drought-tolerant.”

“It’s important to try to be proactive about it,” Efseaff said. “A lot of people aren’t used to watering their trees in summer, but that water source is gone. The water table has really dropped. It doesn’t take a whole lot to take care of them.”