This is a bit off-topic, but it is related to the drought. The Houston tree canopy is in great danger of substantial tree loss. Here is an article from today's paper with some watering tips:
Grass-roots effort: Save the trees
• Group calls on residents to water now or drought might take its toll
By KATHY HUBER
HOUSTON CHRONICLE
Houston’s trees need help. It may not be obvious yet, but without substantial rain in the next few weeks the effects of this year’s drought may greatly reduce the area’s green canopy in five years, experts say.
The city stands to lose millions of trees, according to Trees for Houston, which has planted about 419,000 trees across the area in 28 years. The organization is calling for a grass-roots watering effort, urging residents and civic associations to water trees, even those on public property.
Trees for Houston is stretching its budget to keep young trees it has planted watered once or twice weekly, spokeswoman Randi Cleary said.
The city is partnering with other organizations as much as possible to water public trees, city forester Victor Cordova said. City crews, for example, are watering 7,000 of the 25,000 trees planted in January for Arbor Day. The Texas Department of Transportation is responsible for the rest.
Symptoms vary among species, but early signs of drought damage are yellowing leaves and leaf drop throughout the crown, Cleary said. As damage worsens, leaves die from the bottom of the tree upward and from the inside of the canopy outward. In some cases, leaves simply wilt, or turn brown along their edges.
Erratic weather the past three years has been tough on trees. A lesser drought in 2009 was followed by heavy rains interspersed with dry months in 2010. Droughtstricken trees also invite disease and insects that could further weaken and kill them during the next few years.
“Lack of rain, wind and extreme temperatures contribute to tree stress,” said Jack Swayze, a district manager with Davey Tree Expert Co. “Secondary problems then set in. We’ve seen extreme numbers of large limbs drop, brittle with loss of water.”
Damage from the current drought will be seen in the next five to 10 years, reducing the environmental benefit of the tree canopy — not to mention the beauty of healthy trees, Swayze said.
To help save the urban forest, Trees for Houston recommends a deep, thorough soaking once a week during the growing season. A watering schedule that maintains a lawn in a drought is not adequate to maintain trees.
Watering tips
A rule of thumb during a drought is to give a small, 1-year-old tree 28 gallons of water a week, a 2-year-old tree 56 gallons a week, and a 3-year-old 112 gallons a week. But large, mature trees also need help. About 10 gallons per inch of trunk diameter is recommended each week.
“Older, established trees have more extensive root systems, but still might not find enough water in the soil during a drought to stay in good health,” said Mickey Merritt of the Texas Forest Service.
The key, he said, is a long, slow soaking, so water can penetrate deeply into the root zone. Options include:
• Turning the hose on at a little more than a trickle, and letting water soak into the ground under the drip line or canopy until that area is saturated. Move the hose to another area and repeat.
• Using soaker hoses.
• Poking holes in the bottom of 5-gallon buckets and placing them beneath trees, then filling the buckets so the water slowly seeps into the soil.
• Purchasing slow-release systems such as Ooze Tube and Treegator, which Merritt said are beneficial in watering young trees.
Costly options
It may take several hours to water a large tree, Merritt said. But a slow soak reduces runoff and evaporation. Though water bills may still run high, the cost of removing a large dead tree can exceed hundreds of dollars.
Trees also can be helped by removing weeds and grass that compete for water beneath tree canopies. Replacing the grass with 2 to 3 inches of mulch will help conserve soil moisture. (Experts warn against piling mulch against tree trunks, which encourages disease and pest problems.) For homes with irrigation systems, Swayze recommends running a second cycle so water can percolate deeper into the soil.
