When you hear the word fungi, your first thought might be that it’s something harmful. Mushrooms on a damp lawn, or decay inside a trunk. But in this case, mycorrhizal fungi for trees are actually heroes! In fact, they’re one of the best allies your trees can have. Beneath the soil, fungi form powerful partnerships (often referred to as symbiotic relationships) with roots that strengthen, nourish, and improve the resilience of your trees.

And while our team is always here to promote healthy growth through knowledge and care, we also provide safe tree removal services when a tree is beyond saving. Join us and explore the world of mycorrhizal fungi and why you should consider fostering them in your backyard.

The Star of the Show: Mycorrhizae

The Greek term mycorrhizae translates to “fungus-root,” and that’s exactly what it is: a living connection between fungi and tree roots! This relationship isn’t new, and it’s been around for hundreds of millions of years, helping forests survive through climate shifts, droughts, and poor soils.

The process starts when tree roots release chemical signals into the soil. The “chemical signals” tree roots release are mostly sugars, amino acids, and organic acids. Fungal spores in the soil can sense these signals and respond by growing toward the roots and attaching themselves. Once connected, they form a living network, stretching out like threads through the soil. This underground network works as an extension of the root system, dramatically increasing the tree’s reach to nutrients in the soil.

In return for sugars and carbohydrates from the tree, the fungi bring back water, minerals, and nutrients. This partnership is so effective that many trees just simply can’t grow to their full potential without it.

How Does Mycorrhizae Benefit Your Trees?

Trees supported by fungal partners have a long list of advantages. Here’s what makes the partnership so powerful:

Improved growth and development: The fungi provide extended reach, allowing young and mature trees alike to establish themselves faster and stand sturdier than if they didn’t have fungal support.
Better access to nutrients: Fungi dissolve and deliver nutrients like phosphorus, nitrogen, and zinc straight to the roots, making them usable for growth.
Improved soil texture and balance: Fungal threads bind soil particles together, resulting in a soil that holds air, water, and nutrients in balance!
More water availability: Fungal networks act like sponges, holding onto water during dry periods and slowly releasing it to roots when it’s needed.
Less nutrient loss: Instead of getting washed away during rain, nutrients get trapped in the fungi network, keeping them safe for the next time your tree needs them.
Natural defense system: Fungi help roots resist harmful bacteria, root rot, and even insect attacks by outcompeting or blocking the invaders.

To summarize: encouraging mycorrhizal fungi for trees makes your soil healthier and your trees tougher!

Types of Mycorrhizal Fungi

Arbuscular Mycorrhizal Fungi (AMF)

This type is the most widespread and associates with the majority of tree species, especially maples, ashes, and fruit trees. These fungi actually enter root cells, creating tree-like structures inside that allow for fast nutrient transfer. Though invisible above ground, their presence can make a noticeable difference in tree vitality.

Ectomycorrhizal Fungi (EMF)

These fungi form a protective layer around roots rather than entering them. They work well with hardwoods like oaks, beeches, and birches, as well as evergreens like pines and spruces. EMF fungi are also responsible for producing many of the mushrooms you see in forests, a sign that the underground system is alive and active.

Trees in New York City That Are Compatible With Mycorrhizal Fungi

Not every tree in New York City connects with fungi in the same way. Here are the species that benefit most:

Arbuscular partners: Maples (red, sugar, and Norway), ashes, honey locusts, and fruit trees such as apples and pears form strong bonds with AMF. These trees often grow more actively and show improved nutrient absorption in fungal-rich soils.
Ectomycorrhizal partners: Oaks (white, red, and pin), beeches, birches, and pines are classic EMF species. Many of these are planted in Central Park, Prospect Park, and other NYC green spaces, where fungi help them adapt to compacted soils and urban stress.
Native supporters: Sassafras, sweetgum, and dogwoods are among local species that naturally partner with fungi. Choosing native trees boosts fungal compatibility and supports biodiversity in your local city!

By planting or caring for these species with fungi in mind, New Yorkers can improve tree resilience against compacted soil, air pollution, and fluctuating weather which are challenges that urban trees face every day.

How To Begin Growing Mycorrhizae in Your Tree Soil

Encouraging fungi isn’t too complicated. Here’s how to get started:

Limit soil disturbance: Constant digging or rototilling tears apart the underground fungal web.
Encourage plant variety: A mix of trees, shrubs, and groundcovers supports different types of fungi, making the soil more familiar with fungi.
Go easy on synthetic fertilizers: Switch to slow-release or organic fertilizers so any dangerous chemicals don’t discourage your trees from partnering with fungi.
Feed the soil with organic matter: Add mulch, compost, and fallen leaves. As they break down, they provide the carbon and nutrients fungi need to survive.
Be picky with fungicides: Avoid broad-spectrum fungicides near your trees unless necessary because they can sometimes harm the healthy fungi as well.
Keep moisture steady: Opt for deep, steady watering so that swings between bone dry and soggy don’t stress out both tree roots and fungi.
Choose local, native trees: These species have evolved with the fungi in your region and often form the strongest symbiotic relationship.
Learn which species benefit most: For example, pines, oaks, and fruit trees rely heavily on fungi, while some plants like brassicas (cabbage family) don’t form mycorrhizal relationships at all.

How To Maintain Mycorrhizal Fungi

Once fungi are established, you’ll want to keep them healthy so that your trees can continue benefiting from the fungi. Here’s how:

Check the condition of your soil: Test for organic matter and pH. Aim for a balanced range depending on your tree type.
Water with purpose: Thoughtful watering trains roots (and fungi) to grow deeper.
Keep organic layers fresh: Replace mulch every year or two. This steady input of natural material keeps fungi fed and active.
Avoid compacting root zones: Parking cars, stacking heavy items, or constant foot traffic crushes the delicate fungal networks underground. Create designated pathways to protect soil around trees.
Encourage natural groundcover: Plants like clover or low-growing native flowers can help shade the soil, add nutrients, and support fungal health.

Things To Be Careful Of When Increasing Mycorrhizal Fungi

While fungi bring major benefits, a few factors can limit their success:

Compacted soil: When soil is packed down, fungi can’t spread their networks. Gently loosening the soil with compost or mulch can help, but avoid aggressive tilling.
Loss of topsoil: Erosion washes away organic matter and fungal spores. Use mulch, groundcover, or native grasses to hold soil in place.
Climate and soil conditions: Extremely sandy soils may not hold enough moisture, while heavy clay may drown roots and fungi alike. Adjusting with organic matter can balance both extremes.
Overwatering or underwatering: Fungi need a balance; too much water suffocates them, too little dries them out. Regular and thorough monitoring is essential, especially during the fungi growth phase.

Your Trees Love Mycorrhizal Fungi

Fungi may be invisible, but their role in tree health is fundamental. By supporting mycorrhizal fungi for trees, you’re giving your landscape a built-in system for better health in every area. Help mycorrhizal fungi thrive, and your trees will reward you with years of strength and beauty above ground!