Complete Guide to Tree Health in Missouri

Missouri's 15 million acres of forestland make it one of the most heavily forested states in the central United States. Spanning USDA Hardiness Zones 5b through 7a, the state bridges the ecological gap between eastern deciduous forests and the Great Plains grasslands, creating an unusually diverse tree flora for its latitude.

The Ozark Plateau dominates the southern half of the state, with its oak-hickory and shortleaf pine forests ranking among the most species-rich temperate forests in the country. Northern Missouri's glaciated plains support oak-dominated savannas and bottomland forests along the Missouri and Mississippi rivers. The Bootheel region in the southeast supports remnant bald cypress-tupelo swamp forests reminiscent of the Deep South.

Missouri's tree health management combines the challenges of a broad climate range with urban forestry needs in metropolitan areas like Kansas City and St. Louis. From the post oaks of the Ozark glades to the cottonwoods of the Missouri River bottoms, this guide covers the essential information for keeping Missouri's trees healthy.

Climate and Growing Conditions

Missouri's climate is transitional, with influences from the Gulf of Mexico, the Great Plains, and the continental interior.

Temperature — Northern Missouri (Zone 5b-6a) has winter lows around -15°F to -10°F, while the Bootheel (Zone 7a) may only reach 0°F to 5°F. Summer heat regularly exceeds 95°F with high humidity, particularly in the eastern lowlands. Growing season ranges from 175 to 220 days.

Precipitation — Annual rainfall ranges from 34 inches in the northwest to 50 inches in the southeast. Missouri is prone to both drought and flooding, sometimes in the same year. Spring and early summer thunderstorms can be severe.

Ice Storms — The Ozarks are particularly susceptible to damaging ice storms, which can break limbs and fell entire trees. The January 2009 ice storm was one of the most damaging natural disasters in state history.

Soil Diversity — Northern Missouri has deep glacial loess soils. The Ozarks feature thin, rocky, cherty soils over limestone and dolomite. Southeastern Missouri lowlands have deep alluvial soils. Soil pH varies widely, from 4.5 in Ozark forests to 7.5+ in northern clay soils.

Humidity — High summer humidity promotes fungal diseases, particularly in the eastern half of the state.

Common Trees of Missouri

• Flowering Dogwood (Cornus florida) — Missouri's state tree. Found in forest understories throughout the Ozarks. Threatened by dogwood anthracnose.
• White Oak (Quercus alba) — Dominant on upland sites across the state. Missouri's most important timber tree.
• Post Oak (Quercus stellata) — Characteristic of dry Ozark ridges and glades. Very drought-tolerant.
• Northern Red Oak (Quercus rubra) — Found statewide in mesic forests. Susceptible to oak wilt.
• Black Oak (Quercus velutina) — Common in dry-mesic forests. Also susceptible to oak wilt.
• Shortleaf Pine (Pinus echinata) — Missouri's only native pine. Historically widespread in the Ozarks; now much reduced.
• Eastern Redcedar (Juniperus virginiana) — Aggressively expanding across Missouri's landscape. Important for wildlife but competes with native grasslands.
• Sugar Maple (Acer saccharum) — Found in mesic forests, especially in the eastern Ozarks and along rivers.
• Bald Cypress (Taxodium distichum) — Native to the Bootheel swamps. Increasingly planted in urban areas for flood tolerance.
• Hackberry (Celtis occidentalis) — Adaptable to many conditions. Growing in popularity for urban planting.
• Green Ash (Fraxinus pennsylvanica) — Formerly widespread. Being lost to EAB across the state.
• Pecan (Carya illinoinensis) — Native to river bottoms. Important nut and shade tree in southern Missouri.
• Sassafras (Sassafras albidum) — Abundant on disturbed sites and forest edges.
• Persimmon (Diospyros virginiana) — Common on poor soils and field edges. Valued for wildlife.

Top Tree Health Threats in Missouri

Emerald Ash Borer (EAB) Detected in Missouri in 2008. Now found in most counties across the state. Continues to spread into the Ozark's native ash stands along streams and rivers.

Oak Wilt Active in multiple Missouri counties, particularly in the Ozarks. Red oak group species die rapidly. White oak group species decline more slowly. Prevention through proper pruning timing is critical.

Oak Decline A complex syndrome affecting red and black oaks in the Ozarks, caused by combinations of drought, defoliation (from spring cankerworm and other defoliators), and secondary attack by red oak borers and Armillaria root rot. A major management challenge in Ozark forests.

Dogwood Anthracnose Caused by Discula destructiva. Has significantly reduced dogwood populations in the Ozarks, especially at higher elevations and in moist, shaded sites. Kousa dogwood is resistant.

Thousand Cankers Disease A threat to Missouri's black walnut trees. Caused by a fungus carried by the walnut twig beetle. Missouri is a major black walnut producer, making this disease economically significant.

Pine Bark Beetles Southern pine beetle (Dendroctonus frontalis) and other bark beetles attack shortleaf pine, particularly in overcrowded stands or during drought. Thinning is the primary management tool.

Jumping Worms Invasive Asian jumping worms are spreading in Missouri, degrading the forest floor organic layer and affecting tree regeneration.

Seasonal Tree Care Calendar for Missouri

Spring (March - May) - Inspect trees for ice storm and winter damage - Plant trees from mid-March through April - Apply mulch 2-4 inches deep in wide rings - Avoid pruning oaks from April through July - Begin EAB treatments for valued ash (late April/May) - Monitor dogwoods for signs of anthracnose

Summer (June - August) - Water newly planted trees during drought (1-2 inches weekly) - Watch for oak wilt symptoms: wilting, browning, rapid leaf drop on red oaks - Monitor for fall webworm, bagworms, and Japanese beetles - Watch for signs of oak decline in Ozark forests - Avoid heavy pruning in summer heat

Fall (September - November) - Excellent planting season: September through October - Resume structural pruning after leaf drop - Remove diseased foliage and fallen debris - Water trees well before ground freezes - Apply fertilizer only based on soil test recommendations

Winter (December - February) - Prune dormant trees (avoid oaks and elms) - Remove ice-damaged branches promptly - Plan species-diverse spring plantings - Manage eastern redcedar encroachment on native grasslands - Inspect for overwintering pests

Missouri Tree Health Resources

• Missouri Department of Conservation — mdc.mo.gov — Forest health, tree identification, and management guides
• University of Missouri Extension — extension.missouri.edu — Research-based tree care and pest management
• Missouri Community Forestry Council — Community tree planting and urban forestry resources
• Missouri Arborist Association — Find ISA-certified arborists in Missouri
• MU Plant Diagnostic Clinic — plantclinic.missouri.edu — Plant disease and pest diagnosis
• Mark Twain National Forest — fs.usda.gov/mtnf — Federal forest management in the Ozarks
• Missouri Invasive Plant Council — moinvasives.org — Invasive species identification and management