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Reduce Tree Stress to Keep Them Healthy

Written by Rhonda Ferree, retired horticulture educator

The most common questions we get in our Extension offices are about trees. Unfortunately, most people do not notice their trees until they show major dieback or leaf drop. Often by the time we get the call, the tree has irreversible damage, and I have no magic formula to save it.

The odd weather patterns the last past few years have left many trees stressed. Stressed trees are less able to fight off pest infestations, and those with other conditions are often impacted sooner. These conditions include trees that are planted too deep, have circling roots, compete for resources, grow in harsh conditions, etc.

To be sure your trees live long, healthy lives, check for these early signs of stress. Leaf scorch, which is browning of the leaf edges and inner vein spaces. Early fall color. New leaves that are smaller or stem sections that are closer together than normal. If a tree is severely stressed, trees make sacrifices to reduce stress on the whole plant. Entire leaves and branches may die. Lower and older limbs usually die before younger ones. Smaller branches are forfeited for larger ones.

To reduce tree stress and keep your trees healthy, following these tips.

WATER trees slowly and deeply. Most plants need 1-inch of water per week during the growing season. When temperatures climb above 90 degrees, plants may need 2 inches of water per week. Irrigate slowly so water percolates into the soil instead of running off. Water where the roots are. A tree's water-absorbing roots are at its drip-line, not congregated around the trunk. Although young trees need more frequent irrigation, even mature trees need water.

APPLY MULCH to limit water loss from the soil. Apply 2 to 4 inches of wood chips, straw or other organic mulching material at the base of the tree. More than 4 inches of mulch may deprive roots of oxygen, and make it hard for water to reach the roots. Spread mulch like a donut, not a volcano, leaving space next to the truck to discourage rot. Avoid using rocks as mulch since they absorb heat and stress roots.

Avoid pruning, fertilization and any other maintenance that encourages tree growth, which results in an increased need for water. Prune only in the dormant season to remove dead and diseased wood, dangerous branches, and suckers from the base of the tree.

Although trees may seem tough and indestructible, they do suffer from human activity – it just takes them longer to show injury symptoms. Two common examples are weedeater damage and adding soil over a tree's root area.

Finally, remember this Chinese Proverb. "The best time to plant a tree is 20 years ago. The second best time is now." Just be sure to plant it properly to avoid problems later.



As horticulture educator, Rhonda Ferree inspired citizens in local communities to grow their own food and improve their home landscapes. She focused on high quality, impactful programs that taught homeowners how to create energy-efficient landscapes using sustainable practices that increase property values and help the environment.

After 30 years with University of Illinois Extension, Rhonda retired in 2018. She continues to share her passion for horticulture related topics as “Retro Rhonda” on social media.

ILRiverHort is a blog that helps people connect to nature and grow.