Oak Wilt: An fungal Parasite

Texas Oak Wilt Map

The Texas Forest Service prepared this map of oak wilt infected areas. From Dallas, to Austin, to San Antonio, oak wilt creates stands of dead trees.

Oak wilt is an fungal parasite that affects the vascular system of an oak tree. On June 18-19, 2014, Dr. David Appel and Jim Houser of the Texas A&M Forest Department updated ISA Certified Arborists, including Shane Kelly of Canopy Tree Service  on the latest treatment techniques.

Arborists care about treating oak wilt because this parasite can wipe out the majority of oak trees in an area if allowed to become established. Oak wilt lives in and feeds off the portion of the tree known as the xylem. The xylem are layers of sieve tubes that move nutrients around the tree by negative pressure caused by water evapo-transpiring through tiny leaf openings known as  stomatas. The presence of the oak wilt prevents the tree from receiving needed water and so it “wilts.” Oak wilt does not always kill the oak tree directly or instantly. The tree, especially red oaks, don’t recognize or respond to the presence of oak wilt right away. They wait until the disease has spread and then initiate a late stage protective response that kills itself. How could the oak tree kill itself? It seals off compartments of the tree and attempts to regrow around the diseased areas. In sealing off those compartments it deprives healthy tree tissue of needed nutrients. The sieve tubes are a crucial part of the process of transpiration. The more sieve tubes that are blocked off due to the late recognition and response to the oak wilt the lower the tree’s chance to survive. White oaks fair better than red oaks because unlike the red oaks, the white oaks actually recognize and respond to the presence of oak wilt while it is a small problem. The fewer sieve tubes that are shut down in an early response to oak wilt the more likely the tree will survive.

Oak Wilt Aerial Spread with Red Oaks

Oak wilt spreads in two main ways: aerial and root grafting. Arial spread of oak wilt occurs mainly in red oaks. The oak wilt creates a fungal mat. Fungal mats are how oak wilt spores are released to affect other trees where spores are released and carried by insects. Fungal mats are only dangerous when a Red Oak dies during the cooler months.  One insect that is particularly troublesome is the nitidulid.  The nitidulid is a hairy beetle that is attracted to fungal spores, fresh tree wounds or any other source of vegetation. The hairy beetle picks up spores from the oak wilt mat and carries them to the next tree they travel to.  Arial oak wilt transfer is highly affected by temperature. Oak wilt spores does not survive above 95 degrees or below 45 degrees. Painting fresh cuts blocks the scent of a recently cut oak tree and prevents the nitidulid from coming to it’s next meal.

Oak Wilt Grafting Spread with Live Oaks

Clusters of trees together have intertwined root systems.  Oak wilt spreads about 75 feet per year through the roots of live oaks.  To prevent the spread of oak wilt in live oaks on ranch land or in rural areas, it is optimal to dig a four foot trench around the tree about 100 feet out from the edge of the affected tree area. In rural areas with ranch land, trenching can be an effective solution, especially if all the neighbors cooperate. Inside the trenched area, the trees are eliminated by pushing them down to kill them quickly. Once the trees are pushed down, another parasite that is a more powerful saprophyte than the oak wilt “Hypoxylon Canker”  and which is more efficient at consuming dead trees will also consume the oak wilt.

City Solution

In a town or on small lots with many utilities, trenching is not practical.  Tree injections performed by a skilled arborist can address the oak wilt. A fungicide called Propiconazole can be injected into the tree by one of two methods:  One method is macroinjection and the other is micro injection. Success rates are fairly equal, but sometimes one can succeed while the other fails.

Oak wilt is a powerful parasite that can attack and kill the most vigorous oak trees. Interestingly, an oak that is already stressed and in defense mode may actually fare better when challenged by oak wilt.

Oak Wilt Spread Myths

Fire wood is often associated with the spread of oak wilt. In order for fire wood to spread it , it would have to be a red oak with fungal mats, or an infected tree immediately transferred to a susceptible root zone. Although oak wilt is a powerful parasite, it is no match for saprophytes such as Hypoxylon Canker that is found in all trees.  Also fire is usually hotter than 95 degrees and  kills the spores.

Tools are another method of transport blamed for spreading oak wilt. Chainsaws are unlikely to spread oak wilt because they are covered with gasoline and oil and produce heat way in excess of the temperature that spores can tolerate. Also, bare metal is not a surface that oak wilt can establish itself on.  Tools that are more likely to spread oak wilt are digging tools such as shovels, picks and back hoes. They work underground in the root zones and are protected from heat. They can possibly have chunks of mud stuck to them with bits of infected root along for the ride.

Best Time to Identify Oak Wilt

The best months to identify oak wilt are May and June in San Antonio.  An arborist will take samples of the tree and put it into a zip lock bag with blue ice and deliver it to Texas A&M lab for analysis.

Oak Wilt has affected trees in 74 counties in Texas and the list is growing.  For information on its spread, check out the article with the Texas A&M Forest Service  If you suspect you have oak wilt, call Canopy Tree Service for an evaluation.


Canopy Tree Service Reputation

San Antonio Tree Company employs local Certified Arborists

If you are looking for a tree company in San Antonio for either a residential or commercial project, Canopy Tree Service is a good choice because the company has more than 17 years experience serving the San Antonio market. Licensed arborists provide free estimates (210) 441-7021 and will find ways to enhance and preserve both the beauty and health of your trees.

Since 2007, we have enjoyed a stellar rating with the Better Business Bureau.  Please check our tree company reputation out with the Better Business Bureau and the rating details at the link below:

Canopy Tree Service Reputation with Better Business Bureau Rating:  A+

Canopy Tree Service are your San Antonio Tree Service experts providing Tree Trimming, Tree Removal, Tree Pruning, Land Clearing and Tree Diagnosis by our Insured and Certified Arborists. We provide quality tree care maintenance and the best tree trimming, cabling and bracing and tree surgery you can rely on. We are licensed and insured to perform general tree care for residential and commercial properties. Our goal as a tree company is perform affordable tree service to keep San Antonio green and to provide the Texas area with valuable landscaping to extend the life of it’s rich trees and shrubs. We give you the best advise on any general tree service for your money. Canopy Tree Service has all the hardware, skills and staff to complete any commercial or residential job.  We will protect your landscape investment whether the trees need cabling and bracing, disease management, pruning, or removal.   Our goal is to provide you with top customer service and we appreciate your Google reviews. We value our reputation and  adhere to the professional practices of the International Society of Arboriculture.  We will strive to exceed your expectations. Thank you.

Our expert tree climbers, grounds men and professional arborist specialize in the following tree service for Commercial or Residential jobs at affordable prices:

San Antonio Tree ServiceTree Trimming

  • Tree Pruning
  • Tree Removal
  • Stump Removal
  • Cabling and Bracing
  • Tree Diagnosis
  • Land Clearing
  • Lot Clearing
  • Bobcat Work
  • Systemic Injections for damaged trees

Palm Tree Pruning Removes Stalks, Fronds

Palm tree pruning differs from Oak tree pruning considerably and these differences stem from the fact that Oak trees and Palm trees belong to two different classes of flowering plants.   Palm trees belong to a species of flowering plant that has more in common with a blade of grass than an oak tree.  Like a blade of grass, they only grow straight up. Palms belong to the Moncocate classification as opposed to the Dicot classification.  An Oak tree is supported by a wood trunk whereas a Palm tree is not made of wood, but rather has a base made up of overlapping leaf base and enlarged cells.  Palms have no cambium to increase the girth or meristems at the end of each branch.    The new fronds grow straight up out of the center and droop further and further down as new ones come out, eventually dying and creating a brown beard at the bottom.  The girth of the palm tree increases as new fibers are added up the middle pushing older fibers outward. The growth pattern of palms is continuous and the brown beard is constantly being re-created.

Reasons for Palm Tree Pruning

  1. Flowers and fruit are falling on a sidewalk and may create a slipping hazard.
  2. The palm tree has an excessive beard that has attracted unwanted rats, raccoons, and hornets.
  3. Broken fronds that can fall on people.
  4. Excessively “Ugly” look.

The last reason bears close examination.  For the health of a palm tree, very, very light palm tree pruning is best.  Overly ambitious palm tree pruning can remove the sun protection a palm enjoys and sap the tree’s energy.

Palm Tree Pruning Canopy Tree Service

Palm Tree Pruning can remove yellow, brown or broken fronds, along with flowers and fruit stalks.

How a Palm Tree is Pruned

A well maintained palm tree easily accessed by a ladder can be one of the easiest trees to trim.  The yellow, brown, and broken fronds and palm flowers and fruit stalks are removed.  If the palm tree is very tall, then the arborist has several choices of equipment to reach the tall palm tree.  A hydraulic lift is the most expensive method but is the least stressful to the tree.  Another consideration is hydraulic lifts cannot be easily used in a backyard.  Another method is where the arborist climbs the tree with a harness attachment and specialized boots with climbing spikes.  The spikes can spread disease unless cleaned between trees. Trimming only when necessary can minimize the stress to the tree.  Canopy Tree Service never tops or cuts the crown off a Palm tree.  If you would like a free palm trimming estimate, call us.

Ball Moss on Your Oak Trees?

Ball Moss

Ball Moss typically thrives in the inner, shady area of the tree canopy.

Are you concerned that ball moss is taking over your trees?  Do you see lots of dead branches? Not to worry.  Ball moss is a non-parasitic plant that lives on other plants without harming them.  So what about the dead branches on your tree?  There’s an explanation for that.  But first, a little background on ball moss.  Ball moss is an epiphyte  that grows in the air.  It does not take anything from the tree.  The tree just gives the ball moss a place to hang.  

Did Ball Moss Cause Dead Branches?

Back to the dead branches.  If you are convinced the ball moss is killing your tree, you have plenty of company.  If you closely inspect your tree, you will see that the concentration of dead branches is mostly on the interior of the tree.  The branches on the tree interior grow in the shade and frequently do not receive enough sunlight to produce enough food to survive.  Once a branch becomes too “sickly” the tree cuts off further support of that branch and allows that limb to die.  Think of it as a form of self-pruning for the tree.  Branches the tree has slated for death are appropriately called “sink.” Ball moss thrives in dim light and it tends to attach itself the the branches that receive the least amount of light.

Ball Moss Removal Techniques

What if you don’t like the way the ball moss makes the tree look even if it is harmless?  There are several methods of removal.  One method that is very labor intensive is to remove it by hand from the live branches being careful not to strip too many leaves off in the process.  Generally removing dead wood from the tree will get a good bit of the ball moss out and improve the look of the tree.  Do it yourself types should be careful of climbing on branches that are heavily infested as they may break off.   Another method, suggested by the Texas A&M Forest Service, is to spray a chemical called Kocide 101 that will cause the ball moss to shrivel and die in about a week.  High concentrations of this can damage the tree so the Texas A&M Forest Services urges much caution.  If the tree is lightly infested, and the look is not frustrating you, control is not necessary. 

If your tree could benefit from a pruning, the quiet a bit of ball moss can be removed in the process.  Careful pruning can also let sunlight in and reduce the presence of more ball moss.  Canopy Tree Service does not use chemical sprays because the wind can blow the spray on the house and cars and sometimes leaves discoloration.  The Native Plant Society offers additional information and pictures of ball moss with seed-pod stalks and a photo of the lower limbs of an oak dying from lack of sunlight that have thick clumps of ball moss.  If you would like an evaluation on how pruning might reduce ball moss, we can visit with you about that at no cost.

Tree Care at Joe’s Crab Shack

At Joe’s Crab Shack in Northwest San Antonio the palm trees were starting to block the view of the sign and the building and had an un-maintained look.  Our challenge was to work around the restaurants’s

Joe's Crab Shack trees receive tree care.

Joe’s Crab Shack trees receive tree care.

open hours, which was seven days a week.  We scheduled the tree care very early in the morning so as to be out of there by 11 am.  We had a crew climb the tree with harnesses and trim the brown fronds while crew members on the ground cleaned up debris and protected any passerby.