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• The oaks in Northwood Hills yards are mature and very valuable. Most are worth thousands of dollars, and in addition to the loss of the tree it is very costly to remove them when they die.
  
  
• Protect your investment. Just because a tree company can prune does not mean they are familiar with oak wilt, or can diagnose it. Call a certified arborist with a reputable company to assess your trees.
  
  
• Due to the various ways oak wilt spreads, every oak is at risk. Oak wilt is spread by insects, contaminated saw blades, stored/moved wood, and through the root systems. The risk is compounded when the tree is cut – providing a fresh wound for the oak wilt fungus to enter the tree.
  
  
• If you absolutely must trim a limb because it's rubbing the roof or has become damaged by wind, SEAL THE CUT IMMEDIATELY WITH TREE WOUND PAINT OR LATEX PAINT. Seal each cut right after it's made... don't wait until the job is finished.
  
  
• Oak wilt cannot be cured. Sprays do nothing. Injections of Alamo™ may extend the life of the tree. Most live oaks defoliate and die in 1 to 6 months after the first symptoms. A few live oaks take longer or survive several years in stages of decline. Red oaks rarely survive and can die as quickly as 3 to 4 weeks following the initial symptoms.
  
  
• If your trees are diagnosed with oak wilt, please email Beautification Chair . We are mapping the outbreak and every reported case helps us assess the risk and keep you informed.

• www.texasoakwilt.org
  
• www.texasforestservice.tamu.edu
  
• www.stopoakwilt.com

Northwood Hills is in plant hardiness zone 8

Good trees for North Texas

We spotted this list in early 2002 in a local newspaper, courtesy of Dave Forehand, director of the Gardens, The Dallas Arboretum

Genus	Common name(s)	Leaf	Flower	Fruit
1. Magnolia grandiflora	Southern magnolia, evergreen magnolia, bull bay
2. Quercus macrocarpa	Bur oak, mossycup oak, blue oak
3. Quercus virginiana	Live oak, Virginia live oak, southern live oak
4. Ulmus crassifolia	Cedar elm
5. Taxodium distichum	Bald cypress, cypress, swamp cypress
6. Carya illinoensis	Pecan, sweet pecan
7. Quercus muehlenbergii	Chinkapin oak, yellow chestnut oak, rock oak
8. Ulmus parvifolia	Chinese elm, lacebark elm
9. Pistacia chinensis	Chinese Pistache
10. Quercus shumardii	Shumard red oak

Photos are © 2001, ArborQuest.com, Inc.

Webmaster's note:
The following article appeared in the January 2002 NHHA Newsletter:

Oak Wilt Disease Threatens Trees in Northwood Hills

The beauty of our homes and winding streets is enhanced by the presence of majestic oak trees -- mostly red oak and live oak -- some of which may be over a hundred years old. But many have been wiped out in recent years by a menacing disease called Oak Wilt. The frightening truth is that our Northwood Hills area has the highest incidence of Oak Wilt in this part of north Texas. So it is crucial that homeowners know the facts about this threat and what they can do to protect their precious trees.

The following information has been extracted from a paper written by Russell N. Peters of Arborilogical Services, Inc., Wylie, Texas:

Oak Wilt is caused by a fungus that blocks the vessels in a tree that carry water and nutrients up to its leaves. The disease is spread by an insect carrying the fungus spores from infected trees overland to healthy trees -- usually in the spring. It can also spread from infected trees to healthy trees by underground root contact. Once a tree is infected, only rarely can the disease be reversed and the tree restored to health. Prevention, on the other hand, has a 90% chance of success. Two methods of prevention are recommended.

First, avoid pruning red oaks and live oaks during the period from mid-February through May. At this time the spore-bearing insect, which feeds on sap, is most active in north Texas and the cuts in a tree's bark caused by pruning attract it.

Second, to prevent spread of the disease by root contact from nearby infected trees, healthy trees can be treated by injecting fungicide into the root flare around their base. This treatment usually provides about two years of protection.

Symptoms of Oak Wilt infection differ by oak species. Symptoms on red oaks are usually seen as an oily green sheen on the leaves that rapidly turns a tan color before they fall off. Symptoms on live oaks vary, but the most common appears as a color change in the veins of the leaves, the lateral veins turning brown while the rest of the leaf remains green. Defoliation often occurs simultaneously.

If your yard contains prized red oaks or live oaks, it will pay you to remain alert to the threat of Oak Wilt. Prune your trees only during the "safe" months after the end of May and before mid-February. And be aware of the condition of oak trees on adjacent property -- watching for any tell-tale symptoms of infection.

You may also want to get acquainted with a local tree service, just in case.

Oak Wilt - more

• Texas A&M's "Plant Pathology web site: plantpathology.tamu.edu
• Texas A&M (Dallas)'s Oak Wilt Information Page
• Oak Wilt Information Partnership
• U.S. Department of Agriculture Forest Service

Texas Cooperative Extension advises (January 2007): "You may call Dale Groom, horticulturist in the Dallas office at 214-904-3050 or Landry Lockett, horticulturist in the Collin County office at 972-548-4233 or Metro 972-424-1460. Either of these horticulturists will be glad to help you."

And here is another item from May 2001:

Oak Wilt Advisory If you prune Red Oaks or Live Oaks from February to May, you must paint the wounds. Beetles eat the spores from infected Red Oaks and pass the Oak Wilt fungus to the new oaks through the wounds. Once an oak has oak wilt, it can pass it on to nearby oaks (100 feet) through interconnecting roots.

Oak Wilt is not an epidemic here, but it is common. You can tell if your Live Oak tree has it by examining the leaves. The leaves will be green, but the veins will be red. The leaves on Red Oaks just turn brown. A final precaution - cover your wood pile with plastic if it has Red Oak logs. They can be from a tree that had the fungus and beetles can it pick up there.

If you have a tree with Oak Wilt, consider treating nearby Oak trees with "Alamo." There's nothing you can do for the infected tree other than removing it.

Thanks to our NHHA member Tamara Hamm, and Texas A&M Agriculture Extension for this Alert information.

Texas A&M Agriculture Extension 
10056 Marsh Ln Ste 101B
Dallas TX 75229-6066
Phone: 214-904-3050 / FAX: 214-904-3080
E-Mail Address: Dallas-tx@tamu.edu
Web Site: Texas A&M Agriculture Extension