About

Ken Obasa, Ph.D., is a professor in the Texas A&M University Department of Plant Pathology and Microbiology, serving as an Extension Specialist with a focus on diseases of small grains and field crops. His research centers on the diagnosis and management of fungal and bacterial diseases affecting crops such as wheat, triticale, corn, sorghum, cotton, peanut, and hemp, particularly in the Texas Panhandle. He investigates virus disease issues of wheat and works on detecting and characterizing new and emerging disease pathogens, conducting investigations to understand pathogen biology and disease epidemiology with the aim of developing effective management strategies. His work includes studying mycotoxins, leading to the discovery of a novel mechanism for fumonisin detoxification. Dr. Obasa's research is driven by stakeholder needs and aims to provide timely, relevant information to support profitable crop production. He has held leadership roles such as chair of the Diagnostic Committee of the American Phytopathological Society and is the current chair of the NCERA-184 branch, as well as serving as an associate editor for Plant Disease journal and reviewer for multiple scientific journals. Additionally, he is the director of the Texas High Plains Plant Disease Diagnostic Laboratory and an adjunct professor at West Texas A&M University.

Research topics

• Botany
• Biology
• Agronomy
• Horticulture
• Virology

Selected publications

• Relative Occurrence and Seasonal Variations of Wheat-Infecting Viruses in Texas

  Plant Disease · 2025-09-24

  article

  Wheat is a top 10 agricultural commodity in Texas, but there is limited understanding of the relative occurrence and seasonal variations of wheat-infecting viruses in the state. In this study, high-throughput sequencing (HTS) was used to profile the wheat virome across the major production regions in Texas, including the Panhandle, Central, and the Southeast. From spring 2021 to spring 2023, a total of 101 wheat samples were obtained through field sampling visits and diagnostic submissions. Four total RNA pools from a subset of these samples (n = 33: 7 to 10 per pool) were subjected to HTS, generating complete or partial genomes of eight wheat-infecting viruses, including barley yellow dwarf virus PAV (BYDV-PAV), cereal yellow dwarf virus RPV (CYDV-RPV), High Plains wheat mosaic virus (HPWMoV), Triticum mosaic virus (TriMV), brome mosaic virus (BMV), wheat streak mosaic virus (WSMV), wheat Eqlid mosaic virus (WEqMV), and wheat umbra-like virus. Subsequent screening of all 101 samples using virus-specific primers revealed varying incidences of WSMV (74.3%), TriMV (68.6%), BYDV-PAV (13.6%), WEqMV (5.7%), HPWMoV (5.0%), BMV (3.0%), and CYDV-RPV (2.0%) across the three seasons. Mixed infections of two to four viruses were more prevalent (65.3%) compared with single infection (18.8%), with coinfections of two wheat curl mite vectored viruses (TriMV and WSMV) being the most common (40%). The study revealed a greater diversity of wheat-infecting viruses in Texas than previously reported and confirmed WSMV and TriMV as the main etiological agents of wheat viral diseases in the state.

  PublisherDOI

• Wheat Disease Loss Estimates from the United States and Canada — 2024

  2025-03-24 · 3 citations

  report
  PublisherDOI

• Estimated Yield Reductions and Economic Losses on Wheat Caused by Disease from 2018 Through 2021

  Plant Health Progress · 2025-01-01 · 4 citations

  article

  Wheat ( Triticum aestivum L.) yield and economic losses caused by pathogens were estimated annually by plant pathologists from 29 U.S. states and Ontario, Canada, from 2018 through 2021. During this 4-year period, plant pathogens caused an estimated reduction of 560 million bushels, with an estimated loss value of US$2.9 billion. Annual losses ranged from 111 million bushels in 2018 to 188 million bushels in 2019. Based on the number of acres planted, the average per-acre loss caused by plant pathogens was US$18.10 across all years and state/province recording estimates. Fusarium head blight (caused by multiple species of Fusarium) was responsible for the greatest overall estimated reduction in yield, followed by stripe rust (caused by Puccinia striiformis) and leaf rust (caused by P. triticina). Although important disease management costs, such as pesticide application, were not considered, the results show the importance of continued plant disease education and research. Quantifying estimated losses associated with plant pathogens impacting wheat remains an important endeavor. Estimates provided by this group of experts are expected to be used as a guide to influence funding for plant disease research by directing Extension and research through both applied and basic efforts. Moreover, the continued effort to quantify plant diseases and their influence on yield losses, as well as the economics of managing plant diseases, will help inform the industries that influence plant disease management and shape on-farm disease management efforts.

  PublisherDOI

• <i>Pantoea</i> -Induced Interveinal Chlorosis (PIC): A New Bacterial Disease of Corn and Sorghum Caused by <i>Pantoea agglomerans</i> Identified in the Texas Panhandle

  Plant Health Progress · 2025-10-28

  article1st authorCorresponding

  The genus Pantoea includes bacteria that have been designated as emerging pathogens because of their increasing numbers of previously unreported hosts, as well as their multidrug-resistant traits. In corn and sorghum, members of the genus are associated with four important diseases: Stewart's wilt caused by P. stewartii, necrotic or white leaf spots or streaks and stalk rot of corn caused by P. ananatis, leaf blight and vascular wilt disease in maize and sorghum caused by P. agglomerans, and, more recently, late-season decline disease of corn and sorghum caused by P. ananatis. In 2023, bright lemon-green foliar discoloration with interveinal chlorosis was observed on wild grasses in the northwest region of the Texas Panhandle. Later in the year, identical symptoms were observed on corn and sorghum plants. Symptomatic plants were also observed to be stunted, delayed in development, including yield-limiting impairment in reproductive growth. In extreme cases, affected plants failed to reach the reproductive growth stage. Diagnosis of symptomatic tissues consistently recovered bacterial isolates that were initially only culturable using phytoplasma media. BLAST searches of 16S rRNA sequences, multilocus sequence analysis, and genome sequence analysis identified the bacterial isolates as most closely related to P. agglomerans. Investigation of a causal role of the bacteria using a representative isolate, B1714, from sorghum, relying on Koch's postulates, resulted in the successful reproduction of the symptoms observed on symptomatic field plants. Bacteria matching isolate B1714 were also successfully recovered from symptomatic tissues, thus satisfying Koch's postulates and attributing a causative role to isolate B1714.

  PublisherDOI

• Western Corn Rootworm (Diabrotica virgifera virgifera LeConte) and Southern Corn Rootworm (Diabrotica undecimpunctata howardi Barber) Identified as Vectors of Late-Season Decline Disease-Causing Pantoea ananatis

  Crops · 2025-10-19 · 1 citations

  articleOpen access1st authorCorresponding

  Pantoea ananatis was recently described as the causative agent of late-season decline, a new bacterial disease first observed affecting field corn plants, in the Texas Panhandle. The rapid spread of the disease throughout the region and the patchy distribution of symptomatic plants in affected fields, as well as routine observations of edge effects, in which plants with severe symptoms are observed on the edges of affected fields, led us to hypothesize that vectors might be involved in the dissemination of the disease pathogen. In this study, we investigated the western corn rootworm (Diabrotica virgifera virgifera LeConte) and southern corn rootworm (Diabrotica undecimpunctata howardi Barber) for any naturally occurring association with P. ananatis and potential to acquire and transmit the bacterial pathogen. Additionally, we investigated the transgenic corn encoding insecticidal Bacillus thuringiensis proteins (Bt) pyramided with RNAi interference anti-rootworm technology for its potential to protect against any larval role in the transmission of the pathogen through their feeding activities on corn roots. We successfully recovered naturally occurring P. ananatis from samples of both rootworm species collected from corn plants in the field. Following acquisition assays, the acquired pathogen was successfully recovered from previously P. ananatis-free adult rootworms, their eggs, as well as first-instar larvae, suggesting an affinity of the bacteria to establish an endosymbiotic and transovarial association with both rootworm species. Additionally, the transgenic Bt corn with RNAi anti-rootworm technology was ineffective in preventing the transmission of the pathogen by the infected larvae. Findings from this study confirm a vector role in the transmission of the disease pathogen.

  PublisherDOI

• Wheat Disease Loss Estimates from the United States and Ontario, Canada — 2023

  2024-07-11 · 1 citations

  report
  PublisherDOI

• Late-Season Decline, a Bacterial Disease of Corn Caused by <i>Pantoea ananatis</i>, Identified in Sorghum

  Plant Health Progress · 2024-01-01 · 2 citations

  articleOpen access1st authorCorresponding

  Foliar symptoms resembling those associated with late-season decline (LSD) disease of corn, caused by the bacteria Pantoea ananatis, were observed in commercial fields of sorghum plants in 2023 in the Texas panhandle. Diagnosis of symptomatic tissues consistently recovered bacterial isolates that were subsequently identified, based on partial sequences of their respective 16S rRNA gene, as P. ananatis. The pathogenicity of a representative isolate on sorghum was investigated using the method of Koch's postulates and resulted in the successful reproduction of LSD-like foliar symptoms identical to those described for corn, as well as those observed in affected sorghum fields.

  PublisherOA PDFDOI

• Genome analysis and hyphal movement characterization of the hitchhiker endohyphal <i>Enterobacter</i> sp. from <i>Rhizoctonia solani</i>

  Applied and Environmental Microbiology · 2024-02-06 · 2 citations

  articleOpen access

  sp. Crenshaw provided the foundation and resources for a better understanding of the ecology and evolution of this endohyphal bacteria in the rhizosphere. The ability to produce indole-3-acetic acid and phenylacetic acid may provide new angles to study the impact of phytohormones during the plant-pathogen interactions. The hitchhiking behavior of the bacterium on a diverse group of fungi, while inhibiting the growth of some others, revealed new areas of bacterial-fungal signaling and interaction, which have yet to be explored.

  PublisherOA PDFDOI

• Wheat Disease Loss Estimates from the United States and Ontario, Canada — 2022

  2023-05-05 · 1 citations

  report
  PublisherDOI

• Molecular characterization of a divergent genetic variant of wheat Eqlid mosaic virus from a Texas wheat field

  Archives of Virology · 2023-08-29 · 2 citations

  article
  PublisherDOI

Frequent coauthors

• Megan Kennelly

  Kansas State University

  28 shared

• John P. Fellers

  United States Department of Agriculture

  10 shared

• Frank F. White

  University of Florida

  8 shared

• Sanzhen Liu

  Kansas State University

  6 shared

• Heather Shinogle

  University of Kansas

  6 shared

• Karen Kelley

  University of Florida

  6 shared

• John M. Tomich

  Kansas State University

  5 shared

• Benjamin B. Katz

  University of California, Irvine

  5 shared

Education

• B.S.

  Ahmadu Bello University

• M.S.

  University of Agriculture

• Ph.D., Plant Pathology

  Kansas State University

• Ph.D.

  University of Florida

Awards & honors

• Chair of the Diagnostic Committee of the American Phytopatho…
• Current chair of the north central research and extension ac…
• Notes associate editor for Plant Disease journal (APS)