Many issues can cause stress to your oak trees and other trees species besides oak wilt. Below are some biotic (living) and abiotic (non-living) problems that are commonly found on Texas trees.
- Leaf Disease Outbreaks Across Texas – Spotting, mottling, blistering, shedding, and deformity of leaves resulting from various fungal infections in the leaf tissue. By James Houser, Texas A&M Forest Service Regional Forest Health Coordinator.
- Bacterial Leaf Scorch – A bacterial infection of many hardwoods, including some oaks. It results in premature browning of leaf margins in late summer and early fall, which is occasionally accompanied by a yellow ring separating green tissue from brown tissue. It can be mistaken for oak wilt in red oaks. Publication by Texas A&M Forest Service.
- Sudden Oak Death – An invasive fungus currently found on the west coast of North America. Symptoms of sudden oak death include oozing cankers on the tree trunk, twig dieback, and wilting of foliage. Publication by Texas A&M Forest Service.
- Biscogniauxia (Hypoxylon) Canker – A common fungus that attacks stressed, damaged, or diseased trees. Indicators include branch dieback, leaf wilting, and bark separating from the tree. The removed bark exposes powdery spores which will turn hard and black, and eventually gray over time. Publication by Texas A&M Forest Service.
- Actinopelte Leaf Spot – A common fungus that affects most oaks in Texas. Symptoms include dark circles and irregular blotches on the tree leaves. Courtesy of the Texas A&M AgriLife Extension Service.
- Oak Leaf Blister – A common fungus affecting new oak leaves. Symptoms include abnormal leaf growth such as bulges, twists, cups, and depressions. Abnormal growth is typically light green in color turning to brown. Courtesy of the Texas A&M AgriLife Extension Service.
- Oak Leaf Rollers – A caterpillar that defoliates new oak leaves in the spring. By James Houser, Texas A&M Forest Service Regional Forest Health Coordinator.
- Fall Webworm – Large tent-like webs of the fall webworm are a common sight in many areas of Texas. Fall webworms feed on many species of broadleaf trees including pecan, sweetgum, persimmon, elm, hickory, maple and other hardwoods. Publication by Texas A&M Forest Service.
- Live Oak Leaf Drop – Live oak leaves start to turn yellow and blotchy in February or early March because they are senescing (or dying off). Then, they will fall off as the tree makes way for new leaves. This is not a good time of year to diagnose diseases; wait until leaves are fully formed in late April to see if they are healthy. This makes live oaks semi-evergreen, not evergreen. Courtesy of the Texas A&M AgriLife Extension Service.
- Ball Moss – A native epiphyte that inhabits the branches of many trees. This flowering plant is non-parasitic and usually does not harm its host tree. Publication by Texas A&M Forest Service.
- Lichen – Lichen forms on tree trunks and branches when fungi and algae grow together. Lichen is not a concern when it comes to tree health, and it may actually be benefiting your tree by providing protection and added moisture. Courtesy of the Texas Plant Disease Diagnostic Lab.
- Mistletoe – A parasitic plant which penetrates the branches of a host tree and absorbs nutrients from it. American mistletoe is a small green plant that is rarely found in oaks. Publication by Texas A&M Forest Service.
- Severe Drought – Drought symptoms include curling, rolling, mottling, scorching, yellowing, and shedding of leaves. It can eventually lead to dieback of twigs and branches, as well as infestation by insects and disease. Courtesy of Kim Camilli, Texas A&M Forest Service.
- Herbicide Damage – Improperly or inadvertently applied herbicides may cause leaves to be curled, discolored, or have dead spots. They can also result in stunted growth and may lead to death. Publication by Texas A&M Forest Service.
- Lightning Damage – A lightning strike to a tree may cause leaves to wilt and die. Courtesy of the Texas A&M AgriLife Extension Service.
- Construction Damage – Trees are often injured or stressed by nearby construction, which can cause symptoms such as branch dieback, smaller or fewer leaves, early fall color, and disease. Courtesy of ISA Trees Are Good.
- Post Oak Issues – Post oaks experiencing periods of drought, flooding, and construction are vulnerable to diseases and pests that can lead to decline. Courtesy of the Texas A&M AgriLife Extension Service.