Landscape Blog

Maintaining Healthy Trees

General Care Recommendations:

1. Watering trees during dry spells will keep all trees healthy and prevent many pest problems. It is important to water until the top 8”-10” of soil is moist. Watering is most important for young trees, trees with restricted areas for root growth and trees growing on south and west facing slopes.
2. Woodchips or bark mulch will keep the soil cooler, reduce competition with grass and weeds, prevent mower/string trimmer damage, hold moisture in the soil and improve the soil as they decompose. Mulch should not be piled against the base of the tree trunk and ideally should cover the entire area inside the drip line of the tree.
3. Avoid construction damage and soil compaction by not allowing vehicles to drive or park under trees and don’t store heavy materials under trees.
4. Fertilizer is not always needed especially for trees in lawns that have regular lawn fertilizer applications. If trees are growing slowly or have pale yellow-green leaves a fertilizer high in nitrogen may be applied.
5. If significant dead wood, mushrooms on the trunks or sudden wilting of trees is observed a certified arborist should be contacted to inspect the trees.

Specific Recommendations:

• Sugar Maple - the general recommendations above are the best options to keep sugar maples healthy. Damage to the root systems, soil compaction, heavy pruning and lack of water will cause premature death of sugar maple.
• Oak – don’t prune from April 1 to July 30 to avoid oak wilt infection. If an oak ( red oaks specifically) suddenly wilts in the summer a certified arborist should be called right away.
• Birch – need cool, moist soil. Very important to mulch and water.
• Basswood – no serious pests. General care OK.
• Ash – watch trees for dieback in the top of the crown and for lots of woodpecker activity. Partially dead or declining ash trees could be removed now and replaced with a different species. Call the Arrest the Pest hotline if symptoms of Emerald Ash Borer are observed:

Arrest-the-Pest Hotline
651-201-6684 (Metro area)
888-545-6684 (greater Minnesota area)
arrest.the.pest@state.mn.us

• Honeylocust – avoid summer pruning including not removing suckers from the base or trunk during the growing season.

10 Recommended Trees for MN:

1. Red Maple
2. Sugar Maple
3. Catalpa
4. Ginkgo
5. Thornless Honeylocust
6. Kentucky Coffee Tree
7. Red Oak
8. White Oak
9. Basswood ( American Linden)
10. Dutch Elm Disease Resistant Elms- Accolade™ , ‘Cathedral’ PP 8683, ‘Discovery’ PP 8684 and Vanguard ™