COLLEGE STATION, Texas (FOX 44) – We are only mid-way through the month of June, and Texas has already seen extreme heat and very little rain this summer – with this trend predicted to continue.
The anticipation of drought can bring many thoughts to mind – from water shortages to increased wildfire risk – but what do drought conditions mean for our trees?
Drought is defined by a relatively long duration with substantially below-normal precipitation, usually occurring over a large area, and Texas is no stranger to drought. According to the U.S. Drought Monitor, in 2011 more than 80 percent of Texas experienced exceptional drought conditions. This drought killed an estimated 300 million trees – 5.6 million being urban shade trees.
According to experts at Texas A&M Forest Service, tree fatalities occur during a drought because drought is a significant stress to trees.
Drought alone may not kill your trees, though it could be the tipping domino of tree mortality, and should be cause for concern.
Secondary pests and diseases are those which attack a tree already stressed by something else, such as a drought or a winter storm. Hypoxylon and most boring insects are considered secondary pests and diseases – with the exception of the Emerald Ash Borer, which attacks both healthy and stressed ash trees.
When a tree is already stressed, then these types of insects and diseases will increase. These secondary insects and diseases not only increase during the time of drought, but for years after a drought or other large stressor event has ended – as it takes time for trees to recover.
What happens to trees during a drought? Ultimately, the lack of water causes trees to photosynthesize less, or make less food, which leads to a lack of nutrients needed to survive.
Without water, a tree cannot generate sugars and cannot utilize those sugars – a necessary part for the entire process of tree growth. When this happens, trees will start to show physical symptoms of the lack of nutrients. While these symptoms can vary from species to species, most trees will begin to show signs of water stress through their leaves.
Just because leaves begin to fall from your tree does not mean the tree is dead. For small trees, you can simply use your thumb nail and scrape some of the smaller twigs – if there is still green underneath, then the tree is not dead. Within a few weeks, it may leaf back out. If you are concerned your tree is dead, contact a certified arborist for a professional opinion.
Reducing tree stress
The most helpful way to reduce stress to your tree during drought conditions is to give supplemental water – though the amount and how often you water will depend on your specific tree and area.
If you begin to see signs of stress in your trees and the ground under your trees is extremely dry, it’s time to begin watering. To test the dryness of the soil, you can take a long screwdriver and stick it in the ground. If the screwdriver doesn’t go easily six to eight inches into the soil, it’s time to water.
Watering can be done with a water hose, soaker hose, sprinkler or bucket – each way being efficient so long as the tree is getting the water it needs. A good guideline for the amount of water your tree needs is two to three gallons per one inch trunk diameter.
A general rule of thumb for newly-planted trees during the heat of the summer is to water them up to three times per week, in the absence of precipitation. Though, you want to make sure the soil is not completely saturated with water at all times.
Larger, established trees may not need much water at all – but extremely high temperatures and lack of precipitation may warrant watering them every couple of weeks.
When watering your trees, adhere to any water use restrictions you may have in your area and try to maximize the water you do give.
An easy tip for watering trees during a drought is to try and mimic what a typical summer looks like for your trees, watering every ten days to two weeks and knowing that it’s okay to not be on a set schedule – just like normal summer rain.
Another way you can help your trees manage drought stress is by mulching. Mulch is an easy and inexpensive option to help your trees because it conserves water, regulates soil temperatures, reduces competition from other plants and improves soil health.
Avoiding tree stress
During times of drought, be extremely cautious not to add additional stresses to your tree, making them more susceptible to secondary insects and diseases. First, do not prune your trees unless absolutely necessary.
The exception to pruning trees during drought is a completely dead branch or one that is a hazard to its surroundings. Another common mistake that can be harmful to your trees during a drought is putting out fertilizer.
During the summer heat, and especially when experiencing drought conditions, monitor your trees for stress symptoms, adding supplemental water when necessary, and continue to enjoy the values trees add to our lives.
For more information on caring for your trees during drought conditions, you can visit: https://tfsweb.tamu.edu/afterthestorm/Drought/.
You can stay informed on drought conditions in your area by visiting: https://tfsfrd.tamu.edu/ForestDrought/.
If you would like to contact a certified arborist, you can visit: http://isatexas.com/for-the-public/find-an-arborist/.