“5 Tree Diseases Killing Oklahoma Trees (And How to Treat Them)
Common Tree Diseases in Oklahoma
Oklahoma’s climate supports a wide range of tree pathogens and pests. Identifying disease early is the difference between a targeted treatment and a removal. The following are the most important threats to Edmond trees.
Oak Wilt
Oak wilt, caused by the fungal pathogen Bretziella fagacearum, is one of the most destructive tree diseases in the United States. Red oaks are highly susceptible and can die within weeks of infection. White oaks are more resistant but not immune. The disease spreads through root grafts between adjacent trees and through sap-feeding beetles attracted to fresh wounds.
Bagworms
Bagworms (Thyridopteryx ephemeraeformis) are a serious pest on eastern red cedars and junipers throughout Edmond. They also attack arborvitae, oak, and other species. Heavy infestations defoliate and kill branches, and severe cases kill entire trees. Hand-pick bags in fall and winter before eggs hatch. Apply Bacillus thuringiensis (Bt) or other labeled insecticides in May when larvae are newly hatched and most vulnerable.
Hypoxylon Canker
Hypoxylon canker attacks stressed trees, particularly post oaks and water oaks. Infected bark peels away to reveal a gray-brown fungal mat underneath. There is no cure. Removal is the only effective option once the disease takes hold. Stress prevention through proper watering and avoiding root damage is the best defense.
Emerald Ash Borer
Emerald ash borer (EAB) has been confirmed in Oklahoma and is moving through the state’s ash tree population. If you have green ash trees on your property, have them professionally assessed now. Early treatment with trunk-injected insecticides can protect high-value ash trees. Waiting until symptoms appear reduces treatment effectiveness significantly.
Cotton Root Rot
Cotton root rot (Phymatotrichum omnivorum) is a soil-borne fungus common in Oklahoma’s alkaline clay soils. It kills trees and shrubs rapidly with little warning. Infected trees often die within days to weeks of showing symptoms. Avoiding poorly drained planting sites and maintaining good soil health are the primary prevention strategies.
Storm Preparation
Before the severe weather season each spring, have an arborist assess your most valuable trees. Look for dead branches, including bark, and co-dominant stems. Remove trees with significant structural defects before wind loads test them. A $500 proactive pruning job before storm season is far less than a $2,500 emergency call after it. Schedule your spring inspection in February or early March, before the storms begin.
