Not out of the woods yet

Faced with summer’s extreme heat and water restrictions, trees suffer more than ever. Understanding tree care and how it differs from turf care not only save’s course trees, but also saves superintendents from wondering what went wrong.

First, determine if the tree is worth saving. Michael Bova, a project specialist at the Davey Resource Group, Kent, Ohio, says to look at the canopy. If the canopy is 80 percent to 90 percent dead, then the tree will definitely not rebound. But, if drought and heat stress signs occur, the canopy is still green, and superintendents take action right away, then the tree will probably make it.

“If you can get the tree through the summer and there is good rainfall in the winter, it’ll probably survive,” Bova says. “If you improve your cultural practices, you’ll probably save it.”

Once survival is determined, the next step is to change cultural practices to undo heat and drought stress. Tchukki Andersen, an arborist with the Tree Care Industry Association, explains a combined watering system can have a negative effect on course trees.

“There are so many more grass roots than tree roots and watering the grass or the turf actually results in overwatering a tree because it can’t take it up as fast as grass can,” Andersen says. “You want to separate the irrigation systems into zones so you are watering the turf at a separate time and volume than when you would water the trees.”

The first thing superintendents should do is water properly, Bova says. “When watering you want to increase the duration and decrease delivery rate, so use a soaker hose,” he says. “Sprinklers deliver water too fast. You have to get water deeper and increase duration without creating runoff.”

Andersen further explains where superintendents should be directing their deep soak watering methods. “Water all over the entire root zone even past where the tree branches extend over the ground,” she says. “Don’t just apply water directly around the trunk. You want to get the water out to those smaller roots that are spreading along the ground, as well.”

Making sure trees are getting properly watered is a pivotal step to ensuring trees don’t suffer during the summer. But, if water restrictions are implemented, then there are a few other options to ensure your trees make it through the summer heat.

Andersen advises superintendents to put a 3-inch layer of mulch around trees to give roots moisture at a deeper level. “Particles within the mulch capture moisture from the chemical breakdown that is going on with wood mulch and it holds that little moisture there against the soil and works itself into the soil so the tree roots have something to grab,” she says.

Bova also suggests using tree growth regulators (TGRs) to assist trees in desperate need of attention. “TGRs help reduce shoot growth and increase root growth. Do on key trees in key areas that really need help,” he says. With increased root growth, the tree will be able to find more water within the soil.

If operating under water restrictions, examine how you are watering your trees. “If you use overhead sprinklers, it’s unlikely your trees are getting enough water because you’re not watering deep enough,” Bova says. “Determine how much water is being applied and how you can change the way it is being applied. You’re not using more water, just making it go deeper.”

There are also multiple things not to do, such as applying fertilizer, when trees are under stress. Andersen understands why superintendents may believe fertilizer is the best solution, especially while under water restrictions. But the nutrients within the fertilizer can cause problems.

“Without water to conduct the fluids through the xylem, the inner tissues of the tree, it is not going to able to uptake fertilizer let alone be able to move it about the tree,” Andersen says. “What ends up happening is that the salt in the fertilizer, usually it is a high nitrogen fertilizer, ends up staying in the root zone and burning the fine roots of the tree.”

Those baby roots are the roots that pull water and nutrients from the soil and feed the tree. When those burn out, the tree is unable to take up nutrients and rebound.

There are no shortcuts when saving trees from heat and drought conditions. Instead, it depends on how badly you want to keep the affected trees,

“You can lose all the trees on the course and keep the grass green or take a little bit of the turf away and keep the trees healthy with mulch, water and a little bit of attention,” Andersen says. “You have to water the trees if you want them.”

Sarah Weingarten is a GCI editorial intern and a student at Ohio University.