Since June 2016, Emerald ash borer (EAB) has been spreading across the state of Nebraska. First confirmed in Omaha, the city’s Parks and Recreation Department has removed over 9,000 of the 15,000 ash trees on its properties since January 2024.
According to the Nebraska Forest Service, around 44 million ash trees in forests, windbreaks, and urban landscapes are expected to be lost to EAB in the coming decades.
The best way to combat the EAB outbreak in Nebraska is proactive replanting with native tree species. Read on to learn more about EAB, how it affects ash trees, and what native trees work best as a replacement.
Why Nebraska's Ash Trees Are in Crisis
EAB is an invasive, wood-boring beetle from Asia that has been eating our nation’s ash trees since 2002. It has killed hundreds of millions of ash trees across the U.S. and has been found in over 35 states, according to the Nebraska Invasive Species Council.
The insects damage ash trees by laying eggs in bark crevices on the trunk and branches. Once the eggs hatch, the larvae tunnel beneath the bark and begin consuming vascular issues that carry water and nutrients, girdling the tree from the inside out.
Unfortunately, all ash trees are vulnerable to infestation, regardless of health or size. This makes replacement the best option to diminish EAB infestations.
Why Replacing Ash Trees With Native Species Matters
Native tree species are adapted to Nebraska's climate and soil, strengthening their resilience to pests and diseases while supporting local ecosystems like streams and rivers. Selecting diverse native species to plant as replacements for ash trees also reduces the risk of future pest infestations.
As a bonus, native species also require significantly less water, fertilizer, and maintenance than non-native species.
Plant Nebraska’s ash tree replacement guidance can provide more information on why species selection is important.
Best Native Trees to Replace Ash in Nebraska
Here are some recommendations for native Nebraska tree species to replace ash trees. Note that your selection should account for site conditions, such as soil type, shade, windbreak, wildlife, and more.
- Kentucky Coffee Tree (Gymnocladus dioicus) – This tree’s tough, drought-tolerant nature is great for Nebraska’s variable climate. It has attractive compound leaves, an interesting winter silhouette, and low pest and disease pressure. Kentucky Coffee Trees are great for parkways and residential yards. “Kentucky Coffee Trees share the same broad canopy and resilience as ash trees, making them great replacements,” says David Olson of the Davey Institute.
- Dutch Elm Disease (DED)-Resistant Elm Varieties – Tree varieties like Princeton, Jefferson, Valley Forge, and New Harmony were bred specifically to fill the role that American elm once held, but with rigorous breeding programs that reduce the risk of repeating the DED crisis. These trees are great for parkways and large lots. “Varieties like Princeton, Valley Forge, and New Harmony provide the classic elm canopy while withstanding Nebraska’s climate,” says David Olson of the Davey Institute.
- American Linden or Basswood (Tilia americana) – These trees feature fragrant summer blooms that are great for pollinators, dense shade from their canopies, and the ability to adapt to Nebraska soils. They’re particularly well-suited to eastern Nebraska and are fairly drought-tolerant when they reach maturity.
- Swamp White Oak (Quercus bicolor) – Swamp White Oaks are best for properties in eastern Nebraska. It tolerates seasonal moisture fluctuations better than most oaks and is excellent for native wildlife. This tree features attractive exfoliating bark and a strong form.
- Black Walnut (Juglans nigra) – This tree is a distinctly Nebraska native species that is a great long-term investment for shade and wildlife. It requires proper spacing and siting, as it produces a chemical that can inhibit nearby plants. “Leaving around 50 to 80 feet of space around the tree’s trunk will help other plants to avoid the juglone zone. Juglone is a naturally occurring chemical that acts as a natural herbicide to competing plants,” says Dr. AD Ali of the Davey Institute.
Planting Tips for Ash Replacement Trees in Nebraska
The best time to plant replacement trees in Nebraska is in the early fall or early spring. In early fall, warm soil temperatures and increased rainfall help roots establish before winter, while early spring allows trees to establish all summer before the season changes.
Successful tree plantings in Nebraska to help with EAB infestations also require:
- Diverse species – Planting a mixture of tree species not only creates an interesting aesthetic for your yard but also decreases pest infestation and disease spread.
- Proper planting – Dig a hole slightly wider than the root ball of the tree you are planting, but only as deep as the root ball itself. If the tree is coming from a container or burlap, gently loosen the roots to prevent them from girdling. Place the tree in the hole with the trunk flare sitting slightly above the surface.
- Mulching – Apply a 2- to 3-inch layer of organic mulch over the root zone without piling it against the trunk.
- Watering – Young trees need to be watered consistently, around 1 inch per week, for their first few seasons. Water deeply and slowly to promote root growth.
When to Replant & How to Time It With Ash Removal
Replacement trees need time to establish before your ash trees are removed. Ideally, replacement trees should be planted just outside the existing ash tree’s dripline on the east, south, or west side of the tree. North placements generally don’t provide enough sunlight for a young tree to become established.
Once the ash is removed, the replacement tree will have a head start in survival.
Let Davey Help You Replace Your Ash Trees in Nebraska
Davey’s certified arborists in Omaha, NE and the surrounding areas have the expertise to help you identify ash trees on your property and determine what replacement would work best for your specific landscape.
FAQs: Replacing Ash Trees in Nebraska
Ash trees can be saved after an infestation, but it depends on how far the infestation has progressed and the overall health of the tree. In Nebraska, many urban ash trees are in a less-than-ideal state for treatment.
Kentucky Coffee Trees and Common Hackberry trees are two quicker-growing native replacements for ash trees. Avoid planting River Birch and Eastern Cottonwood trees, which grow extremely fast but come with a myriad of other issues. Birch tends to have a short lifespan, while Cottonwoods often grow too big for a normal yard.
Place replacement trees just outside the dripline of the old ash tree to avoid root competition and minimize risk of damaging the new tree when the ash tree is removed.
Kentucky Coffee Trees and Basswood are great alternatives for residential yards and parkways.
