Rhizoctonia Management: Essential Steps for Protecting Corn and Soybeans

The seedling disease rhizoctonia (caused by the fungus rhizoctonia solani) can be detrimental to your soybean and corn crops. You can spot rhizoctonia by looking for reddish-brown lesions at or just above the soil line. Damage caused by rhizoctonia can include rotted and underdeveloped root systems and dry or corky stems.¹
The more you know about rhizoctonia root rot, the disease’s risk factors and options for rhizoctonia treatment, the better prepared you’ll be to proactively keep your crop healthy in the critical post-planting period.

Risk factors that increase susceptibility to rhizoctonia

Fields where you’ve previously experienced outbreaks of rhizoctonia in soybeans and corn are at a higher risk of infection than fields that have never been infected. If you’ve gone through multiple seasons of corn-soy rotations, you might also be at higher risk.
The disease residue and inoculum can live in your soil and in plant debris, lurking and ready to attack next season’s crop.

Soil type and conditions

If you farm on soils that have high organic matter or are poorly drained and heavy, your risk of rhizoctonia root rot is higher compared to farming in other soil types. The disease can occur under a variety of moisture conditions, though it thrives in moist, not saturated, soil. It also prefers warmth, especially temperatures ranging from 60 F to 95 F.²

Plant and environmental stress

Several factors in your fields can delay crop emergence and boost your risk for disease overall and rhizoctonia in particular before plants reach V4.³ Among them are:

• Wet, compacted or waterlogged soils
• Herbicide injury
• Feeding from soilborne insects and pests such as nematodes
• Hail and other weather damage
• Reduced tillage, which can leave pathogen inoculum to build up in the planting zone

Resistance status in corn and soybeans

As of this writing, there are no commercial corn or soybean cultivars with strong rhizoctonia resistance. Some soybean genotypes have shown partial resistance or field tolerance, but that depends on several factors including environment and the strain of the pathogen. Consider rhizoctonia resistance ratings when selecting seed varieties.

Effective management strategies for rhizoctonia treatment

You can implement several management strategies to mitigate the risk of rhizoctonia root rot on your farm. Here are some of the most effective approaches.

Cultural practices for rhizoctonia root rot treatment

First, consider rotating corn or soybean with a non-host crop such as wheat or barley. This can reduce the level of inoculum in your soil.⁴
Look for opportunities to improve soil drainage. Avoid planting in high-risk fields where rhizoctonia has been a problem or where conditions would create the perfect ecosystem for the fungus. Invest in high-quality seeds that will produce vigorous seedlings.

Rhizoctonia fungicide seed treatments

Seed-applied fungicides should be among the primary management tools in your toolbox. In particular, active ingredients such as sedaxane, penthiopyrad, fluxapyroxad, azoxystrobin and pyraclostrobin can be effective against rhizoctonia.
Most corn seed comes with a standard seed treatment package. You can request additional seed treatments for your soybeans, and your retailer can apply those treatments.
Seed treatments offer protection for between four and five weeks after planting.
Biological seed treatments can offer partial control. In some situations, you might want to use a combination of treatment types to optimize benefits.⁵
You can learn more about the benefits of seed treatment in this BASF video on YouTube and on BASF’s seed treatment webpage. You can also learn more about the benefits of rhizoctonia fungicide and other fungicide treatments.

Integrated disease management recommendations

To provide your farm fields with the highest degree of protection, a systems approach is your best bet. You can implement this kind of model by:

• Assessing field history and soil conditions before you plant
• Prioritizing seed treatment in high-risk fields
• Scouting emerging crops for early symptoms of rhizoctonia
• Practicing crop rotation and residue management

Experts are available to help you make your decisions for rhizoctonia treatment. Reach out to your seed retailer, a nearby extension office agent, or a seed company professional like your regional BASF representative.

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Endnotes

1. University of Illinois at Urbana-Champaign, Department of Crop Sciences. “Seedling Diseases of Soybeans.” farmdoc daily (8):103, Nathan Kleczewski, June 6, 2018, farmdocdaily.illinois.edu/2018/06/seedling-diseases-of-soybeans.html. Accessed 25 Aug. 2025
2. Kelsey Scott and Anne E. Dorrance. “Rhizoctonia Damping-off and Root Rot of Soybeans.” Ohioline, Ohio State University Extension, 8 Feb. 2017, ohioline.osu.edu/factsheet/plpath-soy-1. Accessed 25 Aug. 2025.
3. Oklahoma State University Extension. “Soybean Disease Update – Seedling Diseases.” Pest E-Alerts, Oklahoma State University Extension, 2025, extension.okstate.edu/e-pest-alerts/2025/soybean-disease-update-seedling-diseases.html. Accessed 25 Aug. 2025.
4. North Dakota State University Extension. “Managing of Rhizoctonia Damping-Off, Crown Rot and Root Rot of Sugarbeet.” Ag Hub, NDSU Agriculture, adapted from Crop & Pest Report, 16 June 2022, ndsu.edu/agriculture/ag-hub/ag-topics/crop-production/crops/sugarbeets/managing-rhizoctonia-damping-crown-rot-and-root. Accessed 25 Aug. 2025.
5. Michigan State University Extension. “Fungicidal Seed Treatments for Soybeans.” MSU Extension News, 19 Mar. 2009, www.canr.msu.edu/news/fungicidal_seed_treatments_for_soybeans. Accessed 25 Aug. 2025.