What Is Root Rot? The Hidden Killer Lurking Beneath Your Landscape

You water faithfully. You fertilize on schedule. You’ve chosen plants that should thrive in North Georgia. Yet something is clearly wrong—your once-vibrant shrub is wilting despite moist soil, leaves are yellowing for no apparent reason, or that expensive ornamental tree just doesn’t look right. The culprit could be hiding underground where you can’t see it: root rot.

According to the University of Georgia Extension, root rot diseases are “by far the most damaging diseases in Georgia’s landscapes.” The frustrating reality is that by the time above-ground symptoms appear, the damage below ground is often extensive. Understanding what root rot is, why it happens, and how to prevent it can save your landscape plants—and your investment in your Cumming, Suwanee, or Johns Creek property.

Understanding Root Rot: What’s Actually Happening Underground

Root rot is exactly what it sounds like—a condition where a plant’s root system begins to decay and die. Healthy roots are firm and typically white or light-colored. Roots affected by rot become soft, mushy, and brown or black. They may even emit an unpleasant odor, similar to rotten eggs.

The roots are your plant’s lifeline. They absorb water and nutrients from the soil while anchoring the plant in place. When roots begin to rot, they can no longer perform these essential functions. The plant essentially begins to starve and dehydrate—even when surrounded by wet soil—because the damaged roots can’t take up what the plant needs to survive.

What makes root rot particularly tricky is that it progresses underground, out of sight. By the time you notice something is wrong with the leaves or branches, the root system may already be severely compromised.

The Culprits: What Causes Root Rot?

Root rot isn’t caused by a single pathogen. Several soil-borne organisms can attack plant roots, with the most common being:

• Phytophthora species: These water molds are among the most aggressive root rot pathogens and can persist in soil for years
• Pythium species: Another water mold that thrives in wet conditions
• Rhizoctonia solani: A true fungus that causes crown and root rot
• Fusarium species: Fungi that can cause root rot across a wide variety of plants

These organisms share one critical characteristic: they love wet soil. In fact, they need consistently moist to waterlogged conditions to thrive, reproduce, and attack plant roots. This is why root rot is so closely tied to overwatering and poor drainage.

Why Georgia Landscapes Are Particularly Vulnerable

If you’ve gardened in North Georgia for any length of time, you’re intimately familiar with our red clay soil. While clay is nutrient-rich, it creates significant challenges when it comes to drainage. Clay particles are extremely small and pack tightly together, leaving little space for water to drain through. After a heavy rain or irrigation, water can take several days to fully drain from clay soil.

This means roots in Georgia clay are often sitting in waterlogged conditions much longer than roots in sandier soils would be. Add to that our average annual rainfall of 52 inches in the Cumming area—well above the national average—and you have conditions that root rot pathogens absolutely love.

The UGA Extension specifically notes that root rot occurs in “wet soils with limited soil drainage (porosity) or in areas that are over-watered or remain wet due to location of gutters and downspouts, air conditioning units and slopes.” In other words, certain spots in your landscape may be root rot hotspots based purely on how water moves across and through your property.

Recognizing the Warning Signs

Because root rot develops underground, the symptoms you see above ground can be confusing. They often mimic other problems like drought stress, nutrient deficiency, or pest damage. Here’s what to watch for:

• Wilting despite moist soil: This is the classic root rot symptom. The plant looks thirsty, but the soil is wet. Damaged roots simply can’t take up water no matter how much is available.
• Yellowing leaves: Often starting with older leaves or those closest to the soil, yellowing indicates the plant isn’t getting adequate nutrients due to root damage.
• Stunted growth: Plants with compromised root systems can’t support vigorous growth above ground.
• Leaf drop: Leaves may brown at the edges, die, and fall prematurely.
• Branch dieback: Starting from the tips and working back, branches may die as the plant can no longer support them.
• General decline: The plant just looks “off”—lacking the vigor and color of a healthy specimen.

If you suspect root rot, carefully dig around the base of a plant to examine the roots. Healthy roots should be white to light tan and firm. Rotted roots will be brown to black, soft, mushy, and may smell bad. In severe cases, the outer layer of the root will slip off easily, leaving just the central core.

Plants Commonly Affected in Georgia Landscapes

While virtually any plant can develop root rot under the wrong conditions, some are particularly susceptible. In Georgia, common victims include:

• Japanese Holly (Ilex crenata): Extremely prone to root rot in poorly drained soils
• Azaleas and Rhododendrons: Shallow root systems make them vulnerable
• Boxwood: Susceptible to several root rot pathogens
• Annual Vinca: Highly susceptible to Phytophthora
• Leyland Cypress: Often planted in poorly drained areas where they struggle
• Dogwood: Sensitive to wet feet, especially when planted too deeply
• Japanese Maples: Require excellent drainage to thrive

That said, the UGA Extension emphasizes that “all landscape plants (trees, shrubs and flowers) are susceptible to root rot” under the right conditions.

Prevention: The Best Medicine for Root Rot

Once root rot takes hold, it’s extremely difficult to treat—and often impossible to cure. Prevention is absolutely the best approach. Here’s how to protect your landscape:

Improve Soil Drainage

This is the single most important step you can take. For Georgia’s clay soils, the UGA Extension recommends improving soil structure by “incorporating organic matter, good quality compost, or composted hardwood or pine bark.” These amendments help break up dense clay and create pathways for water to drain.

In areas with persistent drainage problems, consider installing French drains or dry creek beds to redirect water away from planting areas. Sometimes raising beds even slightly can make a significant difference.

Avoid Overwatering

This seems obvious, but it’s one of the most common mistakes homeowners make—especially with newly planted trees and shrubs. In clay soil, roots can literally suffocate from watering too frequently. Allow the soil to dry somewhat between waterings. Most established plants prefer deep, infrequent watering over shallow, frequent irrigation.

Plant at the Proper Depth

Planting too deeply is a major contributor to root rot, particularly in clay soil. The root flare—where the trunk meets the roots—should be visible at or slightly above soil level. Burying the root flare restricts air exchange and keeps moisture trapped against the trunk, creating ideal conditions for rot.

Mulch Correctly

Mulch is wonderful for conserving moisture and regulating soil temperature, but too much of a good thing causes problems. Keep mulch to 2-3 inches deep, and never pile it against plant stems or tree trunks. The “mulch volcano” you see around so many trees actually promotes rot and decay.

Choose the Right Plants for Your Conditions

If you have an area that stays consistently wet, don’t fight it with plants that require excellent drainage. Instead, choose species that tolerate or even prefer moist conditions. Native plants adapted to Georgia’s conditions are often more resistant to local disease pressures.

Ensure Good Air Circulation

Proper spacing between plants and selective pruning to open up dense growth helps reduce humidity around plants and allows foliage and soil to dry more quickly after rain or irrigation.

What To Do If You Suspect Root Rot

If you catch root rot early enough—before too much of the root system is damaged—you may be able to save the plant. Here’s what to try:

• Stop watering immediately and allow the soil to dry out as much as possible
• Pull back mulch from around the plant’s base to help moisture evaporate
• Improve drainage around the plant if possible
• Remove any dead or dying branches to reduce stress on the plant
• Avoid fertilizing stressed plants, as this forces new growth the damaged roots can’t support

Unfortunately, for many plants with advanced root rot, removal is the only option. If you do remove a plant killed by root rot, don’t replant the same species in that location without first addressing the drainage issues that allowed the disease to develop. Root rot fungi can persist in the soil for years.

Chemical fungicides exist, but they’re generally not practical for home landscape use. They require accurate identification of the specific pathogen involved, and most products aren’t packaged in quantities appropriate for residential applications.

Professional Drainage Solutions Make a Difference

Sometimes preventing root rot requires more than soil amendments and careful watering. Persistent drainage problems may need professional solutions like French drains, catch basins, grading adjustments, or strategic hardscaping to redirect water flow.

At Pannone’s Lawn Pros & Landscaping, Brad Pannone and the team have spent over a decade solving drainage challenges specific to Forsyth County’s clay-heavy soil and high rainfall conditions. From identifying problem areas to installing effective drainage systems, professional assessment can save you from repeatedly losing plants to root rot.

Protect Your Landscape Investment in Cumming

Your trees, shrubs, and ornamental plants represent a significant investment in your property’s beauty and value. Understanding root rot—what causes it, how to recognize it, and most importantly, how to prevent it—helps protect that investment for years to come.

If you’re dealing with plants that seem to struggle no matter what you do, drainage issues that turn your yard into a swamp after every rain, or simply want to ensure your new plantings get the best possible start, contact Pannone’s Lawn Pros & Landscaping at (678) 294-0351. Serving Cumming, Suwanee, Johns Creek, and the North Metro Atlanta area, we’ll help you create a landscape that thrives in Georgia’s unique conditions.