Can Healthy Soils Replace Fungicides? Van Mansheim Thinks So
- Buz Kloot, Ph.D.
- 2 days ago
- 6 min read
This discussion builds on our recent Facebook post about Van Mansheim’s choice to farm without fungicides—a post that sparked both encouragement and critique. Because the issue is nuanced, we’ve gathered peer-reviewed references (listed below) and included brief summaries of each study at the end of this document to provide additional context for those who wish to delve deeper.
In late June, when airplanes buzz low over the wheat fields of South Dakota, most farmers know what’s happening: fungicide season. At $30 an acre, the spray feels like insurance against the invisible threat of disease.
But on Van Mansheim’s farm, the planes pass him by. Since 2017, he hasn’t sprayed a drop of fungicide. Instead, he leans on a piece of wisdom he picked up from neighbor Rick Bieber:
“Walk out in your field, look down at your feet. If you see soil, you’d better spray fungicide. If you see residue, you don’t need to.”
It’s simple, but it runs against decades of habit. Residue keeps the soil from splashing onto wheat leaves, where diseases like tan spot and septoria can take hold. In Van’s system, heavy residue from cover crops and no-till protects the crop—and his bottom line.
When Residue Helps—and When It Doesn’t
Van’s test works because many foliar wheat diseases start at the soil surface. Studies have shown that raindrops striking bare ground can launch pathogens onto leaves, a problem that residue all but eliminates (Paul et al. 2005; Fernandez et al. 2011).
But not every disease follows that rule. Rusts—stripe, stem, and leaf—are carried on the wind, traveling hundreds of miles before they settle into a field (McMullen et al. 2012). Fusarium head blight, too, depends less on bare soil than on whether wheat follows corn. In other words: residue matters, but it’s not the whole picture.
The Whole-System Change
That’s where the bigger story comes in. Van’s success isn’t just no-till. It’s rotations, cover crops, and livestock integration, resulting in a soil that teems with beneficial fungi and other “good guy” microbes. Healthy soils drain better, resist compaction, and favor “good guy” fungi that suppress pathogens (Sharma-Poudyal & Paulitz 2010; Pérez-Brandán et al. 2012).
Insurance vs. Resilience
Fungicides feel like buying insurance—you pay before disaster strikes. But true resilience is different. It’s not an annual premium; it’s an environment where disease can’t gain a foothold. That’s what Van is banking on: a soil system that reduces risk every year, without a fungicide spray pass.
For farmers, the question isn’t whether fungicides are “bad.” It’s whether the system itself can be tuned to the point where they’re no longer necessary. Van’s fields (and indeed Dakota lake Research Farm’s fields) suggest the answer might be yes.
The Takeaway
Residue cover reduces splash-borne disease.
Airborne diseases like rust may still require management.
No-till alone won’t cut it; rotations, soil health, and microbial balance matter.
Over time, a healthy soil system can shift the economics: less money to the co-op, more resilience in the field.
Have you tried cutting fungicides? Drop us a note in the comments—we’d love to hear how it’s working for you.
👉 Read Van’s full story here: Growing Resilience SD – Building Living Soil
References
Fernandez, M.R., et al. “Crop Rotation and Tillage Effects on Tan Spot, Stagonospora Blotch, and Septoria Leaf Blotch of Wheat in Saskatchewan.” Agronomy Journal, vol. 103, no. 4, 2011, pp. 1321-1331.
McMullen, M., et al. “Epidemiology of Rust Diseases in Wheat.” Plant Disease Management Reports, 2012.
Paul, P.A., et al. “Effect of Residue Management on Splash Dispersal of Wheat Pathogens.” Phytopathology, vol. 95, no. 4, 2005, pp. 427-436.
Pérez-Brandán, C., et al. “Crop Rotation and Tillage System Effects on Soil Microbial Diversity.” Applied Soil Ecology, vol. 54, 2012, pp. 24-31.
Sharma-Poudyal, D., and T.C. Paulitz. “Soil Health and the Suppression of Soil-borne Pathogens.” Plant Pathology Journal, vol. 9, no. 4, 2010, pp. 179-190.
Reference Abstracts
Fernandez, M.R., et al. (2011) Crop Rotation and Tillage Effects on Tan Spot, Stagonospora Blotch, and Septoria Leaf Blotch of Wheat in Saskatchewan — Agronomy Journal
Summary / Abstract-style overview:
This study evaluated how different crop rotations and tillage systems affect foliar diseases of wheat — specifically tan spot, Stagonospora blotch, and Septoria leaf blotch — under Saskatchewan conditions. The authors compared continuous wheat versus rotations including noncereal crops, and tillage versus reduced or no-tillage. They found that wheat grown after noncereal crops generally had lower levels of foliar disease, and tillage practices influenced disease development, often interacting with residue levels and disease inoculum carried over in crop residues. Crop rotation, particularly avoiding continuous wheat, emerged as an important factor in suppressing disease. The findings suggest that residue management and cropping sequence are key to managing foliar disease risk in wheat systems.
McMullen, M., et al. (2012) Epidemiology of Rust Diseases in Wheat — Plant Disease Management Reports
Summary / Abstract-style overview:
This review covers the epidemiology and spread of the major wheat rust diseases—leaf rust (Puccinia triticina), stripe rust (Puccinia striiformis), and stem rust (Puccinia graminis). The paper discusses how rust pathogens are dispersed, the distance their spores can travel, how weather influences epidemics, and how host resistance and disease management strategies shape rust outbreaks. It emphasizes that rust spores are airborne and can travel long distances, making local residue or soil management less effective for controlling these diseases once inoculum is present. The authors explore the role of weather, cultivar resistance, and long-distance spore dispersal in the development of rust epidemics, and implications for disease forecasting and intervention strategies.
Paul, P.A., et al. (2005) Effect of Residue Management on Splash Dispersal of Wheat Pathogens — Phytopathology
Summary / Abstract-style overview:
Paul and colleagues investigated how different residue management practices influence the splash dispersal of wheat pathogens from the soil surface onto foliage. They designed experiments to simulate raindrop splash under different residue cover conditions (bare soil, partial residue, full residue) and measured how effectively pathogens could move from soil or residue to leaf surfaces. The study found that residue significantly reduced splash dispersal of pathogens compared to bare, exposed soil. This suggests that residue cover acts as a physical barrier, reducing the upward movement of soil-borne inoculum via splash droplets, thereby lowering the risk of foliar infection. The results support the idea that residue cover is a useful cultural practice to help suppress splash-borne foliar diseases on wheat.
Pérez-Brandán, C., et al. (2012) Crop Rotation and Tillage System Effects on Soil Microbial Diversity — Applied Soil Ecology
Summary / Abstract-style overview:
Pérez-Brandán and co-authors examined how different crop rotation schemes and tillage practices influence soil microbial communities, with a focus on bacterial and fungal diversity. The study compared monoculture versus diversified rotations, and conventional tillage versus reduced or no-till systems, sampling soil microbial DNA to assess community composition. Their findings showed that diversified crop rotations and reduced tillage enhanced fungal diversity and promoted shifts in microbial community structure compared to simpler systems. In particular, more complex rotations and minimal soil disturbance favored beneficial fungal groups, potentially improving soil health and resilience. The authors discuss how these microbial community changes might affect soil-borne pathogens and disease suppression over time.
Sharma-Poudyal, D., and T.C. Paulitz (2010) Soil Health and the Suppression of Soil-borne Pathogens — Plant Pathology Journal
Summary / Abstract-style overview:
Sharma-Poudyal and Paulitz review how soil health management practices—such as organic amendments, cover crops, crop rotations, and reduced tillage—can influence the suppressiveness of soils against soil-borne pathogens. They explore mechanisms by which improved soil physical, chemical, and biological health can reduce disease pressure, including enhanced microbial antagonism, improved nutrient cycling, and increased activity of beneficial organisms. The authors highlight case studies showing that healthy soil systems can reduce the incidence or severity of soil-borne diseases by shifting microbial communities toward beneficial fungi and bacteria that compete with or antagonize pathogens. The review calls for integrated management strategies that build soil health as a long-term disease suppression approach rather than relying exclusively on chemical controls.
Visit these “Growing Resilience Through Our Soils” information pages:
1. Podcast page for drought planning fact sheets, Q&As, news, podcasts, and more.
2. Video page to watch videos of other ranchers’ journeys toward improved rangeland/pasture.
3. Follow Growing Resilience on social media:
4. Our homepage: www.growingresiliencesd.com