Mid-Missouri is hard on trees. Our hot, humid summers create the kind of warm, wet conditions where fungal diseases thrive, while the severe thunderstorms, straight-line winds and winter ice storms that roll across Boone County leave fresh wounds where pests and pathogens get in. If you own oak, ash, maple, pine or sweetgum around Columbia, it pays to know what trouble looks like before a treatable problem becomes a removal.
Below are the diseases and pests we see most often on properties across Columbia and the surrounding towns. For each one, here is what to watch for, why it matters, and when it's time to bring in a professional.
The emerald ash borer (EAB) is the single most destructive pest in our region right now, and it kills nearly every untreated ash tree it infests. The adult is a small metallic-green beetle, but the real damage is done by larvae tunneling under the bark and cutting off the flow of water and nutrients. Warning signs include thinning in the upper canopy, sprouts shooting from the trunk's base, vertical bark splits, D-shaped exit holes about an eighth of an inch wide, and heavy woodpecker activity as the birds dig for larvae.
Healthy ash trees can often be protected with timely insecticide treatments, but once an ash is more than about a third dead, treatment is rarely worth it and the tree becomes a hazard. We've covered this pest in depth in our guide to the emerald ash borer in Missouri, including treatment timing and how to decide between saving and removing an ash.
Oak wilt is a fungal disease that clogs a tree's water-conducting vessels, and it can kill a red oak in a single season. Look for leaves that suddenly wilt, turn bronze or brown from the edges inward, and drop while still partly green, usually starting at the top of the canopy. Red oaks are highly vulnerable; white oaks tend to decline more slowly. The fungus spreads through sap-feeding beetles drawn to fresh wounds and through interconnected root systems between neighboring oaks.
Because beetles are most active in spring and early summer, the most important prevention step is simple: avoid pruning oaks from roughly April through July. If you must remove storm-damaged oak limbs during that window, paint the cuts immediately. Oak wilt moves fast, so suspected cases warrant a prompt professional diagnosis.
Anthracnose is a group of fungal diseases that flares up in cool, wet springs, exactly the weather mid-Missouri delivers most years. It commonly affects sycamore, oak, maple, walnut and ash. Symptoms include irregular brown or tan blotches along leaf veins, curled or distorted new growth, and early leaf drop that can leave a tree looking thin by midsummer. On sycamores you may also see twig dieback and crooked branches from repeated infections.
The good news is that anthracnose rarely kills an otherwise healthy tree. The fix is usually cultural rather than chemical: rake and dispose of fallen leaves, improve air circulation through the canopy, and keep the tree well watered during dry spells. Thoughtful tree pruning to open up dense growth often does more good than any spray.
Our ISA-certified arborists diagnose disease and pests and tell you straight whether it's treatable.
📞 Call (573) 242-5335These rust fungi need two different hosts to complete their life cycle: an eastern red cedar (juniper) and a member of the apple family such as crabapple, hawthorn or serviceberry. On cedars you'll spot brown galls that swell into bright orange, gelatinous, finger-like horns after spring rains. On the apple-family hosts, the disease shows up as orange or yellow spots on leaves and fruit. Rusts are mostly cosmetic on established shade trees but can defoliate susceptible ornamentals year after year. Planting resistant varieties and increasing distance between cedars and crabapples is the most reliable long-term answer.
Two leaf-eating pests are easy to confuse but behave differently:
Two slower, more serious problems round out the list. Bacterial leaf scorch affects oak, sycamore, sweetgum and elm; its tell-tale sign is leaf margins that brown and dry as if scorched, often with a yellow band separating the dead edge from green tissue, worsening over several seasons. It is chronic and not curable, so management focuses on keeping the tree vigorous for as long as possible. Dutch elm disease, spread by bark beetles, causes flagging and wilting on individual branches before working through the whole crown. Both call for an honest professional assessment of whether the tree can be managed or should come down.
Many of the issues above are treatable if you catch them early, which is exactly why a trained eye matters. Consider calling for help when you notice any of these:
A professional diagnosis through our arborist consulting and tree health services can confirm what you're dealing with and lay out the safest plan. Sometimes that means treatment and pruning; other times, when a tree is structurally compromised, more than a third dead, or poses a falling hazard after storm damage, professional tree removal is the responsible choice. Hazardous trees become especially dangerous in mid-Missouri's high winds and ice, so it's better to act before the next storm than after.
If something on your oak, ash, maple or pine looks off, don't guess. Our ISA-certified arborists serve Columbia, Boone County and the surrounding towns, and we're glad to take a look. Call (573) 242-5335 for a free consultation and an honest diagnosis of what your tree needs.
ISA-certified arborists serving Columbia & mid-Missouri. Free estimates, honest diagnosis, thorough cleanup.
📞 Call (573) 242-5335