I have flown into Austin from the West Coast twice in the past few months. The first time, in July, I was saddened to see so much of what should have been productive farmland burnt brown by the drought. The second time, in mid-September, I was shocked by the large number of what were clearly dead and dying trees –as many as one-fourth of the trees in the Hill Country were brown. Of course, that’s out in a rural area, and people can’t be expected to water large amounts of woodland, but as the plane flew lower over Austin, just north of Allandale, I could see the same thing in our own neighborhood –maybe 10-20 percent of the trees that make up our beautiful urban forest had turned brown or were losing their leaves.
Did you know that large trees can reduce your electricity bill, reduce the amount of watering your lawn needs, and increase the value of your home? Real estate agent and Allandale resident Brandon Faught says that “given two equal homes on equal sized lots in Allandale, the one with large mature well-maintained trees … can have a value of $10,000 to $20,000 more.” One thing that draws people to Allandale is our wonderful trees.
Conversely, a dead or dying tree will end up costing the homeowner in one way or another. A post on the Allandale ListServ last month reported that someone’s tree had fallen on her house. Even if your tree doesn’t fall on your house, it can be expensive to remove. One neighbor told me that she paid $750 to have a tree removed, “and it wasn’t even a big tree.” Removing a large tree from a backyard could “cost a couple thousand dollars if it’s a really big tree,” says Master Arborist Keith Brown, owner of Austin Tree Experts.
Clearly, then, it is in the homeowner’s best interest to take care of his or her trees. But how to do this during what looks to become the worst drought in Texas history? Of course it is crucial to water trees during this drought, but it is also very important to know how to water them. One thing many people may not realize is that sprinkler systems are set up to water lawns and may not provide sufficient water for trees. “Just sprinkling it and making the grass look green doesn’t do anything for the tree,” says City of Austin arborist Michael Embesi.
How can you determine if your trees are getting enough water? According to Don Gardner’s Watering Guide for Texas, for trees to benefit from a watering, you need to make sure the soil is moist five inches down, one day after you water your yard. A simple test is to see how far a screwdriver can be easily inserted into the lawn –that’s how deep the water got. If it didn’t reach five inches, you didn’t water long enough.
A sprinkler system typically won’t soak the ground to a five-inch depth, so it is not the best way to provide water to your trees. Trees need to be watered slowly and deeply. If you water too much too fast you may have more water run off than soaks into the ground. This is especially the case if the ground is already dry or if you’re on a slope. Brown says that if you have a steep slope, you need to water your tree for 15 minutes at a time, four times a day, if you’re watering it with a hose. Of course, this is not terribly practical for most homeowners. Luckily there are better and easier ways to water your tree.
Probably the best way to water your tree is to get a nice long soaker hose and loop it around the tree several times. According to the City of Austin tree watering guidelines, a very young tree has an immature root system, so you want to water it mostly around the planting area (you might want to water a little beyond that area, though, to encourage the roots to grow out). For a more mature tree, you want to water the area that is directly under the foliage, but not too close to the trunk. Once you get your hose set up, let it run at a nice slow drip for as long as it takes for the water to reach down five inches into the soil. You might need to leave the drip hose going all night.
Another way to water your tree is with a hose-end sprinkler. Don Gardner recommends the cheap kind that just sprays a cone of water into the air. Set it low enough that you can see the droplets –if you see mist, the water pressure is too high; that mist is just going into the air, not your tree.
The watering methods just described can only be used during your once-a-week watering day. Of course you can hand water at any time, but you’ll be out there for a while if you really want to give your tree enough water. Another method that can be used any time is the drip-bucket method: you go out and get a bunch of five-gallon buckets (they sell them at home improvement stores, but sometimes you can get them for free from restaurants) and drill two 1/8-inch holes at the bottom. Fill them with water and let them slowly drip out into the ground. Go inside and watch some football, then come out and fill them up again. Repeat until the ground is soaked.
How often should you water your trees? Embesi says you should aim to water your trees thoroughly twice a month: “You want to try to emulate [the pattern of] a rainfall, which is typically a good inundation every couple of weeks.”
What about mulching trees? The arborists I spoke with stressed the importance of mulch: “In a perfect world, the entire yard would be a four-inch layer of mulch,” says Brown. Embesi would like to see at least 10-15 feet of mulch around the base of a tree, “like a natural forest floor.” Mulch provides critical nutrients that your yard soil may lack and also helps keep soil moisture from evaporating. However, you don’t want to over-mulch, and it is crucial to be sure that the water you provide for your tree is reaching five inches into the soil below the mulch, meaning that after you water the tree you need to brush aside a patch of mulch until you see bare dirt, and make sure that the water reached five inches down into that soil.
So let’s say that you’ve done everything you could, but your tree still looks unhappy. How can you tell if the tree is just stressed or whether it is, in the words of Embesi, “in a tight spiral of decline” and will die no matter what effort you put into it? Some common signs of tree distress are leaf curl, tip dieback (where you can see bare twigs sticking out of the canopy of the tree), early leaf discoloration, and leaf drop, which is often accompanied by the twigs setting buds. According to Embesi, leaf drop is a sign of stress and also a technique that trees use to survive drought: “they will lose their leaves early so they don’t have to use all that energy to maintain the leaves.” At this point, you can still save your tree. Embesi says that it can take months or even years for a tree like this to finally die.
Embesi says that determining when a tree has reached the point of no return is difficult, but some signs include dropping branches (self-pruning), significant bark loss (meaning that the tree is decaying under the bark), and fungus (black spots) on the branches and trunk. Brown says that a tree whose leaves have turned brown and not dropped is a tree that will not make it.
Brown says that many trees that are showing signs of stress, particularly those that have dropped their leaves and set buds, “are at severe risk to die over the winter.” If they’re going to make it, these trees need to be kept watered through the winter.
Of course, the sad fact is that some trees are just not going to make it through this drought. What trees should you plant to replace your lost trees? Embesi recommends a pamphlet put out by the Arbor Day Foundation, called “The Right Tree in the Right Place” (see resources at the end of this article for its internet location). Brown’s recommendations, specifically for Allandale, are live oaks, crepe myrtles, and red oaks (for sloped yards) and bur oaks, cedar elms, and Mexican sycamores (for flat yards). He notes that Chinquapin oaks and Monterrey oaks have become popular due to their resistance to oak wilt, but since they’ve only been planted in Austin for 12-15 years, “they haven’t stood the test of time yet, and there is an element of risk with these trees.”
City of Austin web page on taking care of trees in drought: http://www.ci.austin.tx.us/trees/downloads/watering_guidlines.pdf
How to get a free soil moisture monitor:
“The Right Tree in the Right Place”