The Hidden Helpers: How Mycorrhizal Fungi Support Tree Health

And Why Our Fertilizer Treatments Include Them

When people think of tree care, they usually picture pruning branches or applying mulch.

But what’s happening beneath the soil is just as—if not more—important.

One of the most powerful allies a tree has below ground isn’t its roots…It’s fungi.

Mycelium of mycorrhizal fungi in soil

More specifically, a special type called mycorrhizal fungi.

These microscopic organisms form an incredible partnership with tree roots—one that helps trees grow stronger, resist stress, and absorb more nutrients from the soil. At NWI ArborCare, we incorporate these fungi directly into our deep root fertilizer applications to strengthen trees from the inside out.

Here’s how it works.

What Are Mycorrhizal Fungi?

The term “mycorrhizae” literally means “fungus-root.” These fungi live in the soil and attach themselves to tree roots. But unlike harmful fungi that rot wood or cause disease, mycorrhizal fungi are beneficial—they form a symbiotic (mutually helpful) relationship with the tree.

Once connected, the fungi expand outward into the soil, creating a vast underground network—kind of like adding extra root systems. This network brings water and nutrients (especially phosphorus and micronutrients) back to the tree in exchange for sugars that the tree produces through photosynthesis.

Mycorrhizal fungi greatly increases a trees absorption capacity

How Do Trees Benefit?

Trees growing in natural forests are constantly surrounded by rich biological activity. But in urban and suburban landscapes, soil is often compacted, disturbed, or lacking in organic matter. That’s where adding mycorrhizal fungi makes a big difference.

Mycorrhizal fungi help trees:

• Absorb more water and essential nutrients

• Reduce transplant shock in new trees

• Improve drought tolerance in summer heat

• Strengthen resistance to disease and root pathogens

• Increase fine root development for better nutrient uptake

In short, these fungi supercharge the root system.

The Problem with Urban Soil

Most landscape soils in Northwest Indiana have been stripped of their natural biology. Construction, grading, and lawn maintenance practices destroy the microbial balance that trees rely on. Even well-intentioned fertilizers may not help much if the roots aren’t biologically supported.

That’s why our deep root fertilizer treatments go beyond NPK (nitrogen-phosphorus-potassium). We include:

• Beneficial mycorrhizal fungi

• Humic acids to feed soil biology

• Slow-release nutrients tailored for trees

• Targeted application directly into the root zone

This approach isn’t just about making trees greener—it builds a healthier root-soil system that supports growth for years to come.

Increased root density on plants treated with mycorrhizae.

Want Stronger, Healthier Trees?

If your trees are showing signs of:

• Slow growth

• Thinning canopy

• Drought stress

• Yellowing or nutrient deficiency

…it might be time to give their roots the biological boost they need.

At NWI ArborCare, we offer deep root fertilization with mycorrhizal fungi as part of our tree health programs. It’s a smart, science-backed way to invest in your trees for the long term. Click the button below to schedule an evaluation.

Contact Us