About

Jim Kerns is a Professor and Extension Specialist of Turfgrass Pathology at North Carolina State University, serving as the Department Extension Leader in Entomology and Plant Pathology. He is originally from Wheaton, Illinois, and completed his undergraduate degree in Agronomy at NC State in 2002. He earned his MS in Soil and Crop Sciences from Texas A&M University in 2004 and his Ph.D. in Plant Pathology from NC State in 2008. After working as an Assistant Professor and Extension Specialist at the University of Wisconsin-Madison from 2008 to 2012, he was recruited back to NC State in 2012. His research focuses on the etiology, epidemiology, and management of diseases affecting warm- and cool-season grasses, including ultradwarf bermudagrass diseases, large patch of zoysiagrass, plant parasitic nematodes in turf, and diseases of creeping bentgrass. His program aims to provide research-based disease management recommendations to turfgrass managers, and he manages the Turfgrass Diagnostic Lab. Jim's work involves understanding disease biology and developing cost-effective management strategies, with a strong emphasis on practical applications for turfgrass health and disease control.

Research topics

• Biology
• Botany
• Biochemistry
• Genetics
• Horticulture
• Chemistry
• Food science
• Agronomy

Selected publications

• Fungicidal control options for silvery thread moss on creeping bentgrass putting greens

  International Turfgrass Society research journal · 2025-06-27

  articleOpen access

  Abstract Silvery thread moss ( Bryum argenteum Hedw.) (STM) is a common weed on golf course putting greens. Limited herbicidal options are available for the control of STM. Previous research suggests that certain contact fungicides may have efficacy against STM; therefore, a study was conducted to explore fungicidal options for managing STM on golf course putting greens. The study was conducted in Fayetteville, AR, on a “Pure Eclipse” and “Ninety‐Six Two” creeping bentgrass ( Agrostis stolonifera L.) green. Every combination of the fungicides chlorothalonil, fluazinam, mancozeb, and thiram was tested, along with carfentrazone‐ethyl, an industry‐standard herbicide, and a nontreated control for a total of 17 treatments. Treatments including chlorothalonil were the most effective at reducing STM coverage, while the combination of fluazinam + mancozeb + thiram was moderately effective at controlling STM. In a supplemental study conducted in Blacksburg, VA, chlorothalonil greatly reduced moss coverage, while potassium phosphite and fosetyl‐Al were ineffective. These results give turfgrass managers an alternative to carfentrazone‐ethyl for managing silvery thread moss on their putting greens.

  PublisherOA PDFDOI

• Take‐all root rot response to nitrogen rate and source in ultradwarf bermudagrass

  International Turfgrass Society research journal · 2025-05-23 · 1 citations

  articleOpen accessSenior author

  Abstract Take‐all root rot (TARR) is a problematic disease of ultradwarf bermudagrass ( Cynodon dactylon × Cynodon transvaalensis ) putting greens. The etiology and chemical management of TARR are well characterized, yet little is known about how fertilization management, including nitrogen (N) rates and sources, affects TARR severity on ultradwarf putting greens. To address the lack of knowledge, two separate greenhouse experiments were conducted. In the first of this two‐part greenhouse study, ultradwarf bermudagrass cores were inoculated with Gaeumannomyces graminis and fertilized with ammonium sulfate at rates of 0, 6.1, 18.3, 24.4, 30.5, 42.7, and 48.8 kg N ha −1 week −1 for 8 weeks to investigate inoculated turfgrass performance at different N rates. In the second part of the experiment, four distinct N sources—ammonium sulfate, potassium nitrate, calcium nitrate, and urea—were applied at a rate of 24.4 kg ha −1 week −1 for 8 weeks to investigate inoculated turfgrass performance to different N sources. The turfgrass was evaluated for percent root necrosis and dry root weights. This greenhouse study indicated that N rates at or greater than 18.3 kg ha −1 week −1 would reduce TARR severity on ultradwarf bermudagrass compared to turfgrass that received the lowest N rate at 6.1 kg ha −1 week −1 and the non‐fertilized control. Additionally, turfgrass that received ammonium sulfate as an N source had significantly less necrosis than all other N sources, and urea and the non‐fertilized control had the highest, similar necrosis rates.

  PublisherOA PDFDOI

• Identification of Quantitative Trait Loci Controlling Large Patch (<i>Rhizoctonia solani</i> Anastomosis Group 2-2LP) Resistance in Zoysiagrass

  Phytopathology · 2025-04-22 · 3 citations

  article

  Large patch (LP), caused by Rhizoctonia solani anastomosis group (AG) 2-2LP, is the most impactful disease that affects zoysiagrass ( Zoysia spp.). Currently, there are no resistant cultivars on the market, and the only effective means of control is the application of fungicides. Breeding efforts to develop cultivars with resistance to LP would benefit from an increased understanding of the genetic control of the trait. In this study, an F 1 mapping population containing 179 progeny was developed from crosses between Zoysia japonica ‘Meyer’ (susceptible parent) and Z. matrella plant introduction 231146 (resistant parent). Paternal (AH) and maternal (HA) linkage maps were generated using single-nucleotide polymorphism markers developed from genotyping-by-sequencing analysis. Both AH and HA maps organized into 20 linkage groups and consist of 639 and 817 markers, respectively. LP response was evaluated across four experimental runs through collection of final disease severity, digital image analysis-derived percent incidence, and the area under the disease progress curve. All traits showed significant variance among the population, and genotype and genotype × run effects were found to be significant. Sixteen quantitative trait loci (QTLs) associated with resistance were identified, explaining 2.24 to 10.3% of the total phenotypic variance. After looking for overlap across traits, a potential LP “hotspot” was found on linkage group AH_13 (34.5 to 48.6 cM). Several resistance genes were identified near peak markers. The QTLs and associated markers identified in this study have great potential to be introgressed in breeding populations for the development of LP-resistant zoysiagrass cultivars.

  PublisherDOI

• First Report of Gray Leaf Spot Caused by <i>Pyricularia oryzae</i> on <i>Zoysia japonica</i> in the United States of America

  Plant Disease · 2025-08-13

  articleSenior author
  PublisherDOI

• Review of the biology and management of large patch of warm‐season turfgrasses

  Crop Science · 2025-03-01

  articleOpen access

  Abstract Large patch ( Rhizoctonia solani Kühn: anastomosis group [AG] 2‐2) is a destructive disease in warm‐season turfgrasses worldwide, particularly zoysiagrass ( Zoysia spp.). Developing as an orange or tan color, the disease starts as small, round patches that can eventually progress to several meters in diameter. Large patch results in reduced turfgrass health, loss of turfgrass aesthetics, and playability concerns. There have been many studies conducted on the pathology, development, and management of large patch in turfgrass, yet there are gaps in the literature that must be addressed by the turfgrass community. This review addresses current research needs for large patch on turfgrass, and it also provides a comprehensive summary of all previously published research on the disease. Specifically, the review focuses on the highly sophisticated complex of Rhizoctonia solani , along with the many changes that have occurred with the species complex throughout previous research. This review also highlights the common management methods for large patch, including many cultural practices, but the details of chemical and biological control research are emphasized. The objective of this paper is to provide an intensive review on the completed work for large patch as well as illustrate potential areas that require further research.

  PublisherOA PDFDOI

• Fifteen years of findings: Advancements in spring dead spot research from 2009 to 2024

  Crop Science · 2024-09-22

  articleOpen access

  Abstract Spring dead spot ( Ophiosphaerella spp.; SDS) is one of the most detrimental diseases to warm‐season turfgrasses, particularly bermudagrass ( Cynodon spp.), growing in climates where cold temperatures induce dormancy. The pathogen can infect the crowns, stolons, rhizomes, and roots of bermudagrass most of the year, but infection in the fall predisposes the turf to winter injury and plant death. Symptoms typically appear the following spring, making management of SDS challenging. Moreover, the biology, epidemiology, and management of SDS are not fully understood. Ample research has been conducted on SDS which was thoroughly summarized before 2009 by Tredway et al. Since then, 18 new research papers have been published over the last 15 years that have further clarified the biology, epidemiology, and management of SDS. This review seeks to compile, update, and summarize research developments on SDS from 2009 to 2024. Research developments over the last 15 years include an increased understanding of the biology and infection mechanisms of the Ophiosphaerella species that cause SDS, a greater knowledge of the epidemiology of the disease and factors that affect its distribution, as well as improved cultural and chemical management practices for SDS.

  PublisherOA PDFDOI

• Blend ratios and mixtures of brown patch susceptible and resistant tall fescue cultivars

  Agronomy Journal · 2024-10-12 · 1 citations

  articleOpen access

  Abstract Brown patch ( Rhizoctonia spp.) is a major disease of turf‐type tall fescue (TF) [ Schedonorus arundinaceus (Schreb.) Dumort., nom. cons.]. Many cool‐season turfgrass lawns consist of species mixtures or cultivar blends, but the exact proportion of resistant cultivars in blends and mixtures to effectively reduce disease has not been well documented. A field study was conducted in West Lafayette, IN, and Blacksburg, VA, during 2022 and 2023 to determine the brown patch severity of various blend ratios (0%, 25%, 50%, 75%, and 100% by weight) using a brown patch susceptible and resistant TF cultivar. Additionally, mixtures (90% and 10% by weight, respectively) of TF and Kentucky bluegrass ( Poa pratensis L.) with a susceptible and resistant TF cultivar were evaluated. Seasonal appearance/turf quality and brown patch severity were visually determined, and area under the disease progress curve (AUDPC) was calculated. Turf quality and brown patch severity were similar at both locations. Additionally, blends and mixtures containing ≥75% of the resistant cultivar maintained higher average visual quality across both locations compared to the susceptible cultivar alone. Between the two mixtures, the inclusion of a resistant TF cultivar maintained higher canopy density and increased the proportion of TF at both locations. Blends and mixtures containing ≥75% of a resistant cultivar reduced brown patch AUDPC by 71% and 83% in 2022 and 2023, respectively, when compared to the 100% susceptible cultivar. This field study reinforces the importance of selecting resistant TF cultivars to reduce seasonal brown patch symptoms in cool‐season turfgrass lawns.

  PublisherOA PDFDOI

• <i>Phytophthora nicotianae</i>: A Quick Diagnostic Guide for Black Shank of Tobacco

  Plant Health Progress · 2024-01-01 · 3 citations

  article

  Phytophthora nicotianae is an oomycete pathogen that causes black shank of tobacco and is a major threat to tobacco production worldwide. P. nicotianae has been reported on 255 plant genera. Tobacco roots and crowns are the primary areas for disease symptoms, but lower canopy leaf lesions can arise following initial infection. P. nicotianae can be isolated with semiselective media from symptomatic tissue, contaminated water, and soil samples. The objective of this diagnostic guide is to provide a collection of current descriptions and methods for the symptomology, isolation, storage, and identification of P. nicotianae.

  PublisherDOI

• Brown patch severity of five tall fescue cultivars as influenced by summer nitrogen rates

  Crop Protection · 2024-06-05

  article
  PublisherDOI

• Turf-Type Tall Fescue Brown Patch Resistance as Influenced by Morphological Characteristics

  Plant Health Progress · 2024-01-01 · 3 citations

  article

  Brown patch (caused by multiple species of Rhizoctonia and Rhizoctonia-like fungi) is one of the major turfgrass diseases impacting turf-type tall fescue [ Schedonorus arundinaceus (Schreb.) Dumort., nom. cons.] lawns during the summer season. Selection of tall fescue cultivars with brown patch resistance is an important cultural management practice to reduce disease severity and limit reliance on fungicides. A greenhouse experiment was conducted to quantify differences in brown patch resistance among 15 tall fescue cultivars and correlate disease resistance with plant morphological characteristics. Prior to R. solani inoculation, leaf blade width, sheath width and length, endophyte stem infection, and relative growth rate were measured. Disease resistance was determined as a percentage of the canopy blighted as measured using digital image techniques. Brown patch severity after 21 days in Experiments 1 and 2 ranged from 36.7 to 72.7% and 20.8 to 41.8%, respectively, among all cultivars. There were significant differences among morphological characteristics for the cultivars. Increased brown patch was associated with cultivars with a faster growth rate, wider sheath width, and decreased sheath length. This study demonstrates the importance of cultivar selection for reducing brown patch severity in tall fescue lawns. Additionally, tall fescue cultivars with higher shoot density and narrow leaves should not be avoided due to concerns of increased brown patch susceptibility.

  PublisherDOI

Frequent coauthors

• L. P. Tredway

  21 shared

• Joseph Roberts

  Clemson University

  17 shared

• David F. Ritchie

  North Carolina State University

  15 shared

• Renée Rioux

  14 shared

• Travis W. Gannon

  North Carolina State University

  13 shared

• Joseph R. Doherty

  University of Maryland, College Park

  12 shared

• Megan Botti-Marino

  Michigan State University

  12 shared

• Wendell J. Hutchens

  University of Arkansas at Fayetteville

  12 shared

Labs

• Structural Pest Management Training & Research FacilityPI