Cover Story

Minimizing Spring Dead Spot

By M. Aaron Tucker, Assistant Professor, Auburn University and Wendell J. Hutchens, Assistant Professor, University of Arkansas

Introduction

Spring Dead Spot (SDS) is one of the most persistent and damaging diseases affecting warm-season turfgrasses that undergo winter dormancy. First documented in 1954 on a bermudagrass lawn in Stillwater, Oklahoma, SDS continues to challenge turf managers across the southern and transition zone of the United States (Wadsworth & Young, 1960; Tredway, 2009). This article outlines the biology of the disease, key infection periods, and the latest cultural and chemical strategies for effective management.

Pathogen Biology

SDS is caused by soil-borne fungi in the genus Ophiosphaerella, specifically O. herpotricha, O. korrae, and O. narmari. These pathogens differ in geographic distribution and turfgrass host preference. In Alabama, O. korrae is likely the most prevalent species (Hutchens et al., 2025).

Disease Cycle and Symptoms

The fungi that cause SDS are ectotrophic root-infecting pathogens, colonizing the outer surfaces of roots, rhizomes, and stolons, leading to necrosis. This damage predisposes turfgrass to winter injury, with symptoms emerging in spring due to the combined effects of fall infection and harsh winter conditions.

SDS is a monocyclic disease, with a single infection cycle per year. Infection occurs in late summer to early fall, when evening temperatures cool and soil temperatures drop consistently below 70°F. Symptoms appear in spring as circular or semicircular patches of dead turf, ranging from six inches to several feet in diameter. Severe outbreaks can result in large, coalesced areas of turf loss, with recovery taking two to three months after green-up—making proactive management essential.

Cultural Management Strategies

Effective cultural management hinges on understanding the disease's biology. Thatch and organic matter serve as reservoirs for pathogen survival. Practices such as core aerification, verticutting, and fraze mowing during the summer remove thatch and dilute organic matter, thereby reducing inoculum and mitigating spring symptoms (Hutchens et al., 2025).

Conversely, cultural practices such as verticutting and aerification on symptomatic turf in spring can actually hinder recovery. Mechanical stress on already damaged turf slows regrowth, so spring cultivation should be avoided. Proper fertilization, particularly nitrogen applications in late summer/ fall and spring, supports plant health and recovery (Tredway, 2021; Hutchens et al., 2022). Ammonium sulfate has shown efficacy against O. herpotricha, while calcium nitrate is more effective against O. korrae—highlighting the importance of pathogen identification (Tredway, 2021).

Chemical Management Strategies

Chemical control with fungicides is most effective when timed correctly. Applications should occur during fall as soil temperatures drop consistently between 65-55°F. Current research is refining this window using the Battaglia-Hutchens cooling degree-day model to optimize timing (Battaglia et al., 2024).

The modern demethylation-inhibiting (DMI) fungicide mefentrifluconazole offers strong SDS suppression, while older DMIs like propiconazole and tebuconazole provide moderate efficacy (Clarke et al., 2020). Select succinate dehydrogenaseinhibiting (SDHI) fungicides—like isofetamid, penthiopyrad, and pydiflumetofen—also provide excellent control but carry a higher risk of resistance. Rotating SDHIs with DMIs is recommended to preserve efficacy.

Precision Application Technologies

Advancements in GPS-guided sprayers allow for targeted fungicide applications. Mapping disease areas in spring and early summer enables precise fall fungicide treatments, reducing both cost and environmental impact (Booth et al., 2021; Henderson et al., 2025).

Conclusion

Understanding pathogen biology, the disease cycle, and optimal application timing is essential for managing SDS. Continued research is uncovering pathogen-specific responses to cultural and chemical strategies, offering promising avenues for more refined and effective control.

Literature Cited

Battaglia, M., Hutchens, W. J., & Roberson, T. (2024, November). Development of a Fungicide Application Timing Model for Spring Dead Spot Using Cooling Degree-Days. In ASA, CSSA, SSSA International Annual Meeting. ASA-CSSA-SSSA.

Booth, J. C., Sullivan, D., Askew, S. A., Kochersberger, K., & McCall, D. S. (2021). Investigating targeted spring dead spot management via aerial mapping and precision-guided fungicide applications. Crop Science, 61(5), 3134-3144.

Clarke, B. B., Vincelli, P., Koch, P., & Chou, M. Y. (2020). Chemical control of turfgrass diseases 2024.

Henderson, C., Haak, D., Mehl, H., Shafian, S., & McCall, D. (2025). Precision mapping and treatment of spring dead spot in bermudagrass using unmanned aerial vehicles and global navigation satellite systems sprayer technology. Precision Agriculture, 26(2), 38.

Hutchens, W. J., Booth, J. C., Goatley, J. M., & McCall, D. S. (2022). Cultivation and Fertility Practices Influence Hybrid Bermudagrass Recovery from Spring Dead Spot Damage. HortScience, 57(2), 332-336.

Hutchens, W. J., Anders, J. K., Butler, E. L., Kerns, J. P., McCall, D. S., Miller, G. L., & Walker, N. R. (2025). Fifteen years of findings: Advancements in spring dead spot research from 2009 to 2024. Crop Science, 65(1), e21367.

Tredway, L. P., Tomaso-Peterson, M., Perry, H., & Walker, N. R. (2009). Spring dead spot of bermudagrass: A challenge for researchers and turfgrass managers. Plant Health Progress, 10(1), 32.

Tredway, L. P., Soika, M. D., Butler, E. L., & Kerns, J. P. (2021). Impact of nitrogen source, fall fertilizers, and preventive fungicides on spring dead spot caused by Ophiosphaerella korrae and O. herpotricha. Crop Science, 61(5), 3187-3196.

Wadsworth, D. F., & Young, H. C. (1960). Spring dead spot of bermudagrass. Plant Dis. Rep, 44, 516-518.