What Is Mycorrhizae and Why Is It Important?

Modern farming, gardening, and soil management in the United States increasingly focus on root health and soil biology, not just fertilizers. One of the most important biological systems supporting plant growth—often working silently underground—is mycorrhizae.

Mycorrhizae play a critical role in nutrient uptake, water efficiency, soil structure, and long-term plant resilience. Understanding what mycorrhizae are and how they function helps growers, landscapers, gardeners, and land managers make better decisions for sustainable productivity.

What Is Mycorrhiza?

Mycorrhiza  refers to a mutually beneficial relationship between plant roots and specific soil fungi. The word comes from Greek:

• Myco = fungus

• Rhiza = root

In this symbiotic relationship:

• The fungus attaches to or penetrates plant roots

• The plant supplies carbohydrates (energy) to the fungus

• The fungus supplies water and nutrients to the plant

This association has existed for over 400 million years and is present in most natural ecosystems across North America.

Plant Roots ⇄ Mycorrhizal Fungi
   Sugars  ⇄  Water & Nutrients

Why Mycorrhizae Matter in Modern Agriculture and Gardening

In many U.S. soils, nutrients like phosphorus, zinc, and copper are present but poorly available to plants. Mycorrhizal fungi act as natural extensions of the root system, accessing soil zones roots cannot reach.

This makes mycorrhizae especially important in:

• Row crop farming (corn, soybean, wheat)

• Vegetable production

• Orchards and vineyards

• Lawns and turfgrass

• Landscaping and native plant restoration
  

Types of Mycorrhizae

There are several types of mycorrhizal associations, but two are most relevant for agricultural and horticultural use in the USA.

1. Arbuscular Mycorrhizae (AM / VAM)

This is the most common and agriculturally important type.

Key features

• Penetrates root cells

• Forms tree-like structures called arbuscules

• Found in over 80% of plant species

Common host plants

• Corn

• Soybean

• Vegetables

• Fruits

• Grasses

• Ornamentals

Root Cell
│
├─ Arbuscule (nutrient exchange site)
│
└─ Hyphal network extends into soil

2. Ectomycorrhizae

These form a sheath around roots instead of penetrating cells.

Common in

• Forest trees (oak, pine, spruce)

• Native woodland ecosystems

Less common in crops, but critical for forestry and ecological restoration projects.

Benefits of Mycorrhizae for Plants

1. Improved Nutrient Uptake

Mycorrhizal fungi dramatically increase the absorption of:

• Phosphorus (P)

• Zinc (Zn)

• Copper (Cu)

• Iron (Fe)

• Nitrogen (indirectly)

The fungal hyphae are thinner than plant roots, allowing access to micropores in soil.

Without Mycorrhiza:
Root → Limited soil reach

With Mycorrhiza:
Root + Hyphae → Expanded nutrient zone

2. Enhanced Water Absorption

In drought-prone regions of the U.S., mycorrhizae improve:

• Water uptake efficiency

• Root hydration stability

• Drought tolerance

This is especially valuable in sandy soils and arid climates.

3. Stronger Root Systems

Mycorrhizae stimulate:

• Lateral root development

• Root branching

• Root surface area

Stronger roots result in better anchorage and uniform plant growth.

4. Increased Stress Tolerance

Plants associated with mycorrhizae show better resistance to:

• Heat stress

• Transplant shock

• Salinity stress

• Nutrient imbalance
  

Soil Health Contribution of Mycorrhizae

Mycorrhizae do not only benefit plants—they transform soil function.

1. Soil Aggregation and Structure

Mycorrhizal fungi produce glomalin, a sticky glycoprotein that:

• Binds soil particles

• Improves aggregation

• Reduces erosion

Loose soil → Poor structure
Glomalin-rich soil → Stable aggregates

2. Reduced Nutrient Leaching

Better soil structure and nutrient binding reduce runoff and nutrient loss, helping protect groundwater and nearby waterways—an important concern in U.S. agriculture.

3. Support for Soil Microbial Diversity

Mycorrhizae interact with:

• Beneficial bacteria

• Decomposers

• Other soil organisms

This creates a balanced and resilient soil ecosystem.

Cultivation and Use of Mycorrhizae

Where Mycorrhizae Naturally Occur

Mycorrhizae are naturally present in:

• Undisturbed soils

• Grasslands

• Forest ecosystems

• Regenerative farming systems

They are often reduced or absent in soils exposed to:

• Heavy tillage

• Excessive chemical use

• Soil sterilization

• Long-term monocropping
  

How Mycorrhizae Are Applied in Agriculture and Gardening

1. Seed Treatment

Mycorrhizal spores are applied directly to seeds so colonization begins at germination.

Seed → Germination → Immediate fungal contact

2. Root Dipping at Transplanting

Seedlings or saplings are dipped in a mycorrhizal solution before planting, ensuring direct root contact.

3. Soil Application

Granular or powder formulations are applied to the root zone and incorporated lightly into moist soil.

4. Drip Irrigation (Special Formulations)

Some products are designed for drip systems, but high filtration and clean water  are required.

Best Practices for Effective Mycorrhizal Use

• Apply early in the crop cycle

• Ensure direct root contact

• Avoid fungicides during establishment

• Maintain moderate soil moisture

• Reduce excessive phosphorus application

Early application = Long-term benefit
Late application = Limited response

Mycorrhizae and Fertilizer Use

Mycorrhizae do not replace fertilizers, but they:

Improve fertilizer efficiency

• Reduce required phosphorus inputs

• Support sustainable nutrient management

This aligns with nutrient stewardship goals common in U.S. agriculture.

Mycorrhizae vs Other Root Enhancers

Aspect	Mycorrhizae	Other Root Enhancers
Nature	Living beneficial fungi	Non-living chemical or organic compounds
Mode of Action	Forms a symbiotic relationship with plant roots	Stimulates root growth through biochemical signals
Duration of Effect	Long-term and cumulative	Short-term and temporary
Root Zone Coverage	Extends root system through fungal hyphae	Limited to existing root area
Nutrient Uptake	Enhances uptake of phosphorus and micronutrients	Does not directly improve nutrient availability
Water Absorption	Improves water access from deeper soil zones	Limited effect on water uptake
Soil Health Impact	Improves soil structure and aggregation	No significant impact on soil structure
Contribution to Soil Biology	Actively supports soil microbial ecosystem	Does not build soil microbial life
Application Timing	Best applied at sowing or transplanting	Can be applied at various growth stages
Frequency of Application	Usually one-time or early-stage application	Requires repeated applications
Compatibility with Fertilizers	Improves fertilizer efficiency	Works independently of fertilizer efficiency
Stress Tolerance	Increases drought and nutrient stress resistance	Provides limited stress relief
Suitability	Ideal for sustainable and regenerative systems	Useful for quick root stimulation
Overall Role	Foundation for long-term root and soil health	Support tool for short-term root response

Common Misconceptions

Mycorrhizae are fertilizers → IncorrectThey work instantly → IncorrectMore product gives better results → Incorrect

Mycorrhizae are biological systems, not chemical stimulants.

Why Mycorrhizae Are Important for the Future of Farming

With rising input costs, soil degradation, and climate variability, mycorrhizae offer:

• Better input efficiency

• Improved soil resilience

• Long-term productivity stability

They support both commercial-scale agriculture and home gardening, making them relevant across the entire U.S. growing spectrum. Mycorrhizae are not an optional add-on—they are a natural foundation of plant and soil health. When used correctly, they enhance root function, improve soil structure, and support sustainable production without disrupting existing nutrient programs.

Frequently Asked Questions

Why do mycorrhizae matter in modern agriculture and gardening?

Mycorrhizae improve nutrient and water uptake, strengthen root systems, and enhance soil structure. They help plants grow more efficiently while supporting long-term soil health and sustainability.

What plants don’t like mycorrhizal fungi?

Plants in the Brassicaceae family such as cabbage, broccoli, cauliflower, mustard, and canola generally do not form mycorrhizal associations. These plants rely on different nutrient uptake strategies.

How do you add mycorrhizae to soil?

Mycorrhizae are added through seed treatment, root dipping during transplanting, soil application, or drip irrigation. Direct contact between spores and plant roots is essential for successful colonization.

What plants need mycorrhizal fungi?

Most crops and plants benefit from mycorrhizae, including corn, wheat, soybean, vegetables, fruits, grasses, ornamentals, lawns, and trees. Over 80% of plant species form mycorrhizal associations.

 What is the role of mycorrhizae in plant growth?

Mycorrhizae extend the effective root system, improve phosphorus and micronutrient uptake, enhance water absorption, and increase plant tolerance to drought and nutrient stress.

What is mycorrhizal application?

Mycorrhizal application refers to introducing beneficial mycorrhizal fungi into the root zone at early growth stages to establish a symbiotic relationship that supports plant and soil health.

Are mycorrhizae safe for the environment?

Yes. Mycorrhizae are naturally occurring soil fungi, non-toxic, and safe for plants, soil organisms, and the environment when used as recommended.