As warm-season turfgrasses awaken with the arrival of spring rains, they become increasingly vulnerable to a destructive fungal disease known as large patch. Affecting primarily bermudagrass and zoysiagrass varieties, this disease causes expansive swaths of brown, dying grass that mar lawns, golf courses, and sports fields across the southern United States. The pathogen behind this devastation is a fungus that thrives in the temperate conditions of early spring, exploiting the vulnerable transition phase when turfgrass exits dormancy. Recent research led by University of Arkansas graduate student Samuel Kreinberg has shed new light on the biology, pathology, and integrated management of this pervasive disease, emphasizing the urgency of understanding its lifecycle and environmental triggers to mitigate its impact on landscape aesthetics and turf functionality.
Large patch disease manifests initially as small, circular patches of discolored grass exhibiting hues ranging from yellow to orange and eventually deep brown as the infection progresses. These patches can coalesce into larger necrotic zones, fundamentally compromising turfgrass integrity. The disease primarily targets warm-season turfgrasses that exhibit dormancy in cooler months, rendering them susceptible during the critical early growth phase in spring. The fungus responsible for large patch remains active in the soil and infected plant debris, and its proliferation is influenced by a complex interplay of environmental factors including soil moisture, temperature fluctuations, and substrate conditions such as pH and nutrient availability.
The recently published article, “Review of the biology and management of large patch of warm-season turfgrasses,” appearing in Crop Science journal, represents a comprehensive synthesis of existing knowledge along with novel insights into disease management strategies. Authored by Kreinberg under the guidance of assistant professor Wendell Hutchens, the review delineates the pathogen’s epidemiology, infection mechanisms, symptomatology, and the implications for turfgrass health and maintenance. This literature review emphasizes the pressing need for multidisciplinary research, incorporating plant pathology, soil science, and turfgrass breeding to develop resistance traits and refined cultural practices tailored to various ecological niches susceptible to large patch outbreaks.
Understanding the pathogen’s lifecycle is crucial for developing effective control measures. The fungus predominantly thrives in cool, wet conditions, particularly during spring and fall when temperatures range between 50°F and 70°F (10°C – 21°C). During these periods, mycelial growth infects crown tissues and roots, disrupting nutrient and water uptake and leading to the characteristic fading and dieback of grass blades. As temperatures rise with the onset of summer, the turfgrass often outgrows the disease, and symptoms diminish naturally. This dynamic necessitates precise timing in the application of fungicides and cultural interventions to interrupt fungal development before irreversible damage occurs.
One of the critical contributions of this study is its detailed discussion on the abiotic factors conducive to the disease’s onset and progression. Soil salinity, pH imbalances, and nutrient deficiencies or excesses subtly modulate fungal virulence and turfgrass resistance. Elevated soil salinity, for example, can stress the grass, weakening its natural defenses and creating a more hospitable environment for pathogen invasion. Similarly, acidic or overly alkaline soils may affect fungal spore germination and host tissue susceptibility. Fertility management emerges as a balancing act; excessive nitrogen fertilization can exacerbate disease severity by promoting succulent, more vulnerable growth, whereas inadequate nutrition may impair the plant’s resilience.
In addition to cultural practices, breeding for genetic resistance represents a promising frontier to manage large patch sustainably. The review highlights gaps in current turfgrass breeding programs concerning large patch resistance. Identification of resistant cultivars and the incorporation of resistance genes through traditional or molecular breeding could reduce the reliance on chemical controls and improve long-term disease resilience. Such endeavors require robust phenotyping protocols and a deeper understanding of the genetic bases underpinning host-pathogen interactions within warm-season turfgrass species.
From a practical viewpoint, Kreinberg and Hutchens underscore that proper lawn maintenance can significantly alleviate large patch incidence. Many turf managers inadvertently worsen the condition by overwatering, creating persistently moist conditions favoring fungal growth. Mowing practices should maintain optimal canopy density to balance sunlight exposure and airflow, reducing humidity at the turf surface. Fertilization schedules must align with growth cycles and environmental conditions to avoid excess nitrogen spikes that impair disease resistance. Together, these cultural approaches form the cornerstone of integrated pest management (IPM) strategies applicable to homeowners, sod producers, golf course superintendents, and sports field managers alike.
To validate their research findings, Kreinberg conducted experimental trials in varied Arkansas environments, including Fayetteville and Alma, focusing on zoysiagrass lawns, which are notably susceptible to large patch. These trials involved monitoring environmental variables, disease progression, and turfgrass response under different management regimes. The results reaffirmed the critical role of environmental modulation and proper cultural techniques in disease suppression. This localized research bolsters the transferability of disease management recommendations while emphasizing regional specificity in pathogen behavior and turfgrass responses.
For the broader public and professionals contending with curious or confused turfgrass conditions in spring, the University of Arkansas Division of Agriculture offers diagnostic services through the Arkansas Plant Health Clinic. Suspected samples of large patch-affected turfgrass can be submitted via local Cooperative Extension offices or directly at the Fayetteville clinic. Accurate disease diagnosis facilitates targeted treatment and helps prevent unnecessary pesticide application, aligning with sustainable turf management goals and environmental stewardship.
The motivation fueling this research was grounded in the identification of knowledge gaps about large patch disease, particularly those aspects previously understudied or misunderstood. Hutchens credits Kreinberg’s meticulous scholarship and dedication in accomplishing the synthesis of a detailed review in a prestigious publication. The article also involved contributions from eminent turfgrass and plant pathology experts such as Mike Richardson, Terry Spurlock, Jim Kerns, and Lee Miller, signifying robust collaborative efforts across institutional lines to address a critical agricultural and horticultural challenge.
Large patch disease represents an intersection of plant pathology, soil science, and turfgrass management, demanding integrated solutions rooted in fundamental biological understanding and practical application. The urgency to mitigate large patch’s impact gains additional importance given the region’s reliance on warm-season turfgrasses for recreational, aesthetic, and ecological functions. As climate variability intensifies and user demands on turfgrass systems evolve, continuous research and adaptive management strategies will be indispensable.
The University of Arkansas System Division of Agriculture, through its Agricultural Experiment Station and Cooperative Extension Service, continues to be at the forefront of advancing knowledge and outreach in turfgrass science. This work exemplifies the division’s mission to connect trusted research with best practices that sustain agriculture, communities, and landscapes. Future directions anticipate enhanced disease-resistant cultivars, refined soil and nutrient management tailored for disease suppression, and the broadened dissemination of research findings to turfgrass stakeholders at all levels.
For those seeking deeper insights or wishing to engage with ongoing research, the Division of Agriculture maintains an active presence across educational platforms, social media, and direct extension services. This ensures that the evolving scientific understanding of turfgrass diseases like large patch benefits a broad audience, from individual lawn owners to professional turf managers, promoting healthier and more resilient grass landscapes.
Subject of Research: Not applicable
Article Title: Review of the biology and management of large patch of warm-season turfgrasses
News Publication Date: 10-Apr-2025
Web References:
- Crop Science Article DOI
- Arkansas Plant Health Clinic
- County Extension Offices
- Arkansas Agricultural Experiment Station
Image Credits: U of A System Division of Agriculture
Keywords: Horticulture, Grasses, Fungi, Soil fungi, Crop science, Aesthetics, Soil science
