About

Kerik D. Cox, Ph.D., is a Professor and Program Leader in the Plant Pathology and Plant-Microbe Biology Section at the School of Integrative Plant Science, Cornell University. He manages a comprehensive program of tree fruit and berry research, extension, teaching, and administration at Cornell AgriTech. His principal research efforts focus on applied disease management for apples and small fruit, emphasizing alternative management practices such as germicidal light, biopesticides, planting systems, covered environment agricultures, disease forecasting, and organic/Generally Recognized As Safe (GRAS) solutions. A significant portion of his work addresses practical or field antimicrobial resistance to agricultural fungicides and antibiotics. His extension activities concentrate on (bio)pesticide education, antimicrobial resistance, disease forecasting, and applied disease management, particularly for apples and controlled environment production in small fruit. In addition to his research and extension roles, Dr. Cox teaches undergraduate and graduate courses in Plant Pathology and Integrated Pest Management (IPM) and provides faculty leadership within his department.

Research topics

• Biology
• Horticulture
• Agronomy
• Genetics
• Biotechnology
• Botany
• Ecology
• Veterinary medicine
• Medicine
• Microbiology

Selected publications

• RejuAgro A as an antimicrobial for fire blight control of pome fruits and beyond

  Nature Communications · 2026-03-11

  articleOpen access

  Fire blight, caused by Erwinia amylovora, severely impacts global apple and pear production. Current control measures rely heavily on conventional antibiotics like streptomycin, oxytetracycline, and kasugamycin, which raise concerns regarding resistance development and environmental impacts. This research introduces RejuAgro A (RAA), an antimicrobial produced by Pseudomonas soli 0617-T307, showing potent activity against E. amylovora, including streptomycin-resistant strains. RAA demonstrates efficacy comparable to streptomycin in field trials, effectively reducing fire blight incidence. Studies on the antimicrobial mechanism reveal that RAA inhibits RNA, DNA, and protein synthesis, distinguishing from that of conventional antibiotics. Furthermore, RAA displays broad-spectrum activity against diverse plant bacterial and fungal pathogens. The RAA biosynthesis gene cluster in P. soli is identified, revealing key genes essential for its production. RAA presents an alternative to traditional antibiotics, potentially enhancing sustainable apple and pear production and addressing antibiotic resistance concerns. Fire blight, caused by Erwinia amylovora, is a devastating disease threatening global apple and pear production. Here, the authors report a new antimicrobial compound from Pseudomonas soli that can effectively control fire blight pathogen in field conditions.

  PublisherOA PDFDOI

• Author Correction: RejuAgro A as an antimicrobial for fire blight control of pome fruits and beyond

  Nature Communications · 2026-04-24

  articleOpen access
  PublisherOA PDFDOI

• Effectiveness of TiO₂ Nanoparticle Application for Treating Fire Blight in Apples

  PhytoFrontiers™ · 2025-03-30 · 1 citations

  articleOpen access

  Fire blight, caused by the bacterium Erwinia amylovora, is a major problem for apple and pear growers. Antibiotics (streptomycin and kasugamycin) are commonly applied during apple blossom in spring to control fire blight. Various alternative strategies for controlling fire blight have been attempted, but they are often less effective and sometimes more costly than antibiotic treatments. Although the catalyzation products of water by nanoparticles (NPs) of the mineral titanium dioxide (TiO 2 ) and UV radiation have been shown to be a highly effective bactericide, they have not been demonstrated to control fire blight. We conducted field studies at a research orchard in central New York and a commercial orchard in eastern New York. We found that applying low concentrations (450 to 1,300 ppm) of TiO 2 NPs combined with natural solar radiation controlled fire blight as effectively as streptomycin, both at the research orchard and at the commercial orchard. TiO 2 NPs are priced comparably to streptomycin, suggesting that TiO 2 NP photocatalysis may be a cost-effective strategy for controlling fire blight. [Formula: see text] Copyright © 2025 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

  PublisherOA PDFDOI

• Early Detection of Botrytis Cinerea Growth via GHz Ultrasonic Imaging of Agar Depletion

  2025-09-15

  article

  Botrytis Cinerea is a destructive fungal pathogen responsible for significant agricultural losses worldwide. In this paper, we demonstrate a GHz ultrasonic imaging method to detect early fungal growth by monitoring nutrient agar depletion. A sessile droplet drying model was developed to establish baseline evaporation dynamics, which were validated experimentally. Using a custom-built portable 1.85 GHz ultrasonic imager provided by Geegah Inc., we correlated return voltage signals with agar thickness, allowing quantification of Botrytis-induced agar depletion. Control droplets exhibited predictable drying and stabilization, while inoculated samples displayed accelerated agar reduction and demonstratable thickness variation in comparison to control experiments. These results suggest that GHz ultrasonic imaging offers potential for a rapid, portable, easy to use platform for on-site pathogen detection, enabling earlier intervention compared to traditional methods.

  PublisherDOI

• Evaluation of Fungicides for the Management of Glomerella Leaf Spot and Bitter Rot on Apple in North Carolina

  Plant Disease · 2025-02-18 · 2 citations

  article

  Glomerella leaf spot (GLS) and bitter rot caused by species in the Colletotrichum gloeosporioides species complex are the most economically devastating fungal diseases of apples in North Carolina. Crop losses have reached 100% in highly susceptible cultivars. In the southeastern United States, management of this disease has predominantly relied on broad-spectrum fungicide programs targeting several summer diseases of apples. To improve control of GLS and bitter rot, field experiments to evaluate the efficacy of multi- and single-site fungicides were conducted over multiple years in a ‘Gala’ research orchard in Mills River, NC, from 2017 to 2019. Fungicides representing different modes of action were applied in a nonrotational program from petal fall until the immediate preharvest period to assess their efficacy in reducing GLS incidence, shoot defoliation caused by GLS, and pre- and postharvest bitter rot. Of the fungicides evaluated, Captan 80WDG (active ingredient [a.i.] captan), Merivon (a.i. fluxapyroxad and pyraclostrobin), Cabrio (a.i. pyraclostrobin), and Aprovia (a.i. benzovindiflupyr) provided good to excellent control against disease caused by Colletotrichum chrysophilum. In these programs, the incidence of GLS, expressed as the relative area under the disease progress curve, ranged from 4.6 to 43.8 in the Captan 80WDG (2019) and the Aprovia (2017) programs, respectively. The incidence of bitter rot at harvest in these programs from 2017 to 2019 ranged from 0.0 to 45.3% in the 2018 and 2017 Captan 80WDG programs, respectively. Conversely, the highest incidences of GLS and preharvest bitter rot were consistently observed in the Inspire (a.i. difenoconazole), Sercadis (a.i. fluxapyroxad), and untreated programs. Shoot defoliation owing to GLS followed a similar trend across the evaluated fungicide programs. In addition to nonrotational fungicide programs, the effect of carrier water pH for applications of captan was evaluated for bitter rot control in Virginia and North Carolina. No differences in captan efficacy were observed at either location. The results of this study will inform the development of new management programs for GLS and bitter rot in the southeastern United States and provide a foundation for the development of new season-long fungicide programs for apple disease management.

  PublisherDOI

• Maximizing the Biocontrol Potential of Bacteriophages: A Call for Critically-Needed Field Research

  Plant Disease · 2025-08-06 · 3 citations

  articleSenior author

  Bacteriophages are viruses capable of infecting bacterial cells. Lytic phages, which infect and kill bacterial cells, are of interest in disease management in human, animal, and plant systems. In plant pathology, the biocontrol of bacterial diseases is of heightened interest because of the lack of efficacious options in many pathosystems. Numerous papers have been published in the past few decades on phage that target plant pathogenic bacteria, and a large majority of these have been focused on phage isolation and characteristics that highlight the promise and potential of phage as biocontrol agents. In contrast, relatively few of these papers have reported results from studies conducted in the field. Of the recent papers (2022 to 2025) reporting field studies, disease efficacy results are inconsistent. We argue that field studies should be an essential component of phage biocontrol research to understand how to best utilize and deploy phages to generate consistently effective disease management.

  PublisherDOI

• Mold in, mold out: Harvest bins harbor viable inoculum that can be reduced using novel sanitation methods to manage blue mold decay of apples

  Postharvest Biology and Technology · 2024-11-22 · 3 citations

  articleOpen access

  Postharvest diseases account for major economic losses worldwide, while also contributing to food waste and loss. Blue mold, caused by Penicillium expansum , is one of the most prevalent postharvest diseases of pome fruit. This necrotrophic fungal pathogen is mycotoxigenic and presents a danger to food safety via the production of patulin. In addition, fungicide resistance threatens blue mold management strategies, creating a need for the development of novel control strategies. The apple storage/processing industry uses wood and plastic harvest bins to harvest and store apples for weeks, months, and even up to 1 year. Although it has been hypothesized that apple harvest bins can serve as a viable inoculum source to incite decay, there is no experimental evidence that has conclusively demonstrated this concept. In this study, we report the presence of Penicillium spp. in apple storage bins (plastic) in the mid-Atlantic USA and developed small scale methods to test 1) if harvest bins can serve as a source of inoculum for blue mold decay and 2) evaluate novel bin sanitation methods as preventative and curative applications. We demonstrated that apple harvest bin materials can serve as a source of inoculum when in direct contact with wounded apples. Additionally, it was shown that UV-C irradiation, sodium hypochlorite, and 2-phenylethanol effectively reduce inoculum viability on plastic materials in a curative fashion. It is envisioned that these findings can aid in the development of large-scale bin sanitation strategies and their applications have great potential to impact a broader range of postharvest pathogens and stored commodities. • Plastic or wooden harvest bin materials can hold viable P. expansum conidia. • New treatments to sanitize both wooden and plastic materials have been tested. • These treatments include UV-C irradiation, sodium hypochlorite, and 2-phenylethanol. • Application of these cause a reduction in P. expansum spore viability in plastic. • The treatments are effective in fungicide sensitive and resistant P. expansum strains.

  PublisherDOI

• An Evaluation of Pruning Programs to Manage Shoot Blight, Caused by the Bacterium <i>Erwinia amylovora</i>

  Plant Disease · 2024-12-27

  articleSenior author

  Blossom infections can lead to shoot blight and, when unmanaged, become systemic and can quickly cause tree death and spread through an orchard via active infections sites producing bacterial ooze. With climate change, increasingly popular high-density training systems, and the susceptibility of many consumers' desired apple cultivars, shoot blight management has become exceptionally challenging despite the diverse management tactics available. To better understand pruning as a management practice, we evaluated 10 pruning programs in two different orchards over the course of 2 years. The pruning programs in this study encompass extension recommendations and grower preferences and include a variety of supplemental chemical applications and sanitation practices to answer three primary questions: (i) How do the impacts of pruning on the management of shoot blight compare between a vertical-axis orchard with mature trees and a high-density planting with young trees? (ii) Do sanitation and ancillary chemical management have a significant impact on shoot blight control achieved through pruning? (iii) How do a variety of pruning programs, including those preferred by researchers, growers, and extension agents, compare in terms of shoot blight management? The impacts of pruning programs were more pronounced in the vertical-axis orchard in terms of reducing infection spread and overall shoot blight incidence. However, in the high-density plantings, pruning programs were mostly ineffective and fire blight spread quickly throughout the trees and planting. Overall, the most aggressive pruning programs, which removed tissue of several seasons of growth, had the greatest impact on fire blight in both plantings. In line with the findings of many previous studies, sanitation or chemical management supplementation was not found to be necessarily beneficial.

  PublisherDOI

• RejuAgro A: A novel antimicrobial for fire blight control of pome fruits and beyond

  Research Square · 2024-09-18

  preprintOpen access
  PublisherOA PDFDOI

• Portable Fungi Growth Detection of Botrytis Cinerea Enabled by Swept Frequency GHz Ultrasonic Imaging

  2024-09-22 · 1 citations

  article

  This paper demonstrates the detection of Botrytis Cinerea using a CMOS-integrated GHz ultrasonic imager. This work expands on the previous work on detecting pathogen growth by introducing new ultrasonic characterization methods of fungal colonies through magnitude, phase, and frequency sweep analysis. A spore solution is created from dishes of Botrytis fungal culture and placed on the ultrasonic imager for 24-48 hours to sporulate and grow under three primary conditions: exposure to only air, with periodically added water, and with a food source to promote growth. Through visual analysis of the return signal magnitude and phase images and using a frame-to-frame visual comparison method, one can determine that growth occurs primarily in the first 12 hours. The addition of Potato Dextrose Agar (PDA) has significantly increased the growth rate and visibility of Botrytis. Frequency sweeps are conducted over a 300 MHz bandwidth centered at 1.85 GHz with 200 kHz steps. The effect of fungal growth on the frequency response is measured as a change in the amplitude of the I and Q components of the reflections as a function of frequency. A shift in frequencies and change in the amplitude is observed in pixel frequency sweeps where Botrytis appears to have developed compared to pixels where no growth was seen optically. The methods developed here facilitate further study in categorizing and differentiating Botrytis growth from other fungal and bacterial growths to create an on-farm diagnostic tool for Botrytis Cinerea.

  PublisherDOI

Frequent coauthors

• Sara M. Villani

  North Carolina State University

  81 shared

• Guido Schnabel

  Clemson University

  51 shared

• Anna Poniatowska

  Instytut Ogrodnictwa

  36 shared

• Verneta L. Gaskins

  35 shared

• Kari A. Peter

  Pennsylvania State University

  31 shared

• Otilia Macarisin

  Agricultural Research Service

  25 shared

• Wojciech J. Janisiewicz

  United States Department of Agriculture

  25 shared

• Katrin M. Ayer

  Cornell University

  25 shared

Labs

• Kerik Cox LabPI

Education

• Ph.D, Plant Pathology

  University of Georgia

  2004