Welcome to the heart of Texas where the sun is shining, the tacos are delicious, and our trees stand tall and proud. Fellow Austinities can attest to how much trees mean to us. Trees are living organisms like us, which means they may face challenges with diseases and health. While there are many tree diseases, there are a few that are common in Austin and Central Texas including Oat Wilt, CottonRoot Rot, and Hypoxylon Canker. We’re going to dive into a description of these diseases and how you can identify if your tree has a disease!
Oak Wilt
Oak Wilt is one of the most notorious tree diseases in Austin. It’s caused by the fungus Bretziella fagacearum (formerly ceratocystis fagacearum).When a tree is infected with Oat Wilt, its water system is invaded and blocked which leads to wilting and possibly death.
Any species of oak tree can be infected with Oak Wilt, but red oak trees are more susceptible to the disease. Common red oak tree species in Central Texas / Austin include Spanish oak, Shumard oak, and blackjack oak. When a red oak tree shows symptoms of Oak Wilt, it can take as little as two to four weeks to die.
White oak trees are more resistant to Oak Wilt but are still at risk and can possibly spread the disease to surrounding trees. White shin oak, chinquapin oak, and Lacey oak have been seen to spread the disease through interconnected root systems but the survival rate is higher than red oaks.
Live oaks are one of the most abundant trees in Austin and while they are a part of the white oak group, they unfortunately succumb to Oak Wilt in the largest numbers. Live oaks usually live in a community with their roots interconnected- once one tree has Oak Wilt, the rest are highly likely to have the disease as well.
Identifying Oak Wilt
There are a few symptoms that can present itself on a tree with Oak Wilt. In Live oaks, the veins on a leaf may turn yellow and eventually brown. This is called veinal necrosis and is usually accompanied by defoliation (fallen leaves).
Red oaks have less distinct symptoms but may display pale green or light brown leaves. The most reliable way to diagnose Oak Wilt in a Red oak is a fungal mat. Fungal mats create cracks in tree bark leading to hollow areas and giving off an odor, similar to fermenting fruit.
Take a look at this gallery of Oak Wilt photos by Texas A&M Forest Service.
Cotton Root Rot
Cotton Root Rot is a fungal disease that infects and attacks a tree’s root system, impeding its ability to absorb water and nutrients. This disease is common when the pH of the soil is over 7.2 and the temperature is hot. In Austin’s hot climate (specifically July and August) root rot is prevalent in trees like maples, elms, and cypress.
Identifying Cotton Root Rot
Because Cotton Root Rot is a fungal infection in the soil, this disease may be caught when it’s too late for trees to recover. The leaves of a tree with Cotton Root Rot will begin to turn yellow or bronze before they wilt shortly after. If the roots are heavily infected, they will decay.
Be sure to properly water your trees and lay fresh mulch, which helps the soil stay cool.
Hypoxylon Canker
Another fungal disease, Hypoxylon Canker causes lesions in weakened, damaged, or stressed trees. During droughts, trees become weakened and are more susceptible to the hypoxylon fungus because of the lowered moisture level of the living wood. The fungus becomes active if the moisture level dips low enough and will invade the sapwood, causing the tree to die. All oak trees are susceptible to Hypoxlyon Canker in addition to pecan, elm, maple, beech, and sycamore.
Identifying Hypoxylon Canker
An early symptom of Hypoxylon Canker is the visible thinning of the crown. As the disease develops, bark will slough off the tree and expose tan, olive green, or reddish-brown powdery spores. If the spores have become visible, this unfortunately means the tree is near death.
During drought seasons, be sure to properly water your tree! See pictures of Hypoxylon Canker by the Texas A&M Forest here.
Keep Your Trees Healthy From Common Diseases in Austin
As we wrap up our discussion on tree diseases in Austin, Texas, remember that knowledge is power. While diseases like Oak Wilt, Root Rot, and Hypoxylon Canker pose challenges, they're no match for our dedication to preserving the beauty of our city's trees.
By staying vigilant, practicing good tree care habits, and seeking professional help when needed, we can ensure that our trees continue to thrive. That's our goal at Legacy Tree Trimming- here's to a greener, healthier Austin for generations to come!