Source: UNIVERSITY OF GEORGIA submitted to
SAM: SUSTAINABLE ANTHRACNOSE MANAGEMENT FOR WATERMELON AND CUCUMBER GROWERS IN THE EASTERN U.S.
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
ACTIVE
Funding Source
OTHER GRANTS
Reporting Frequency
Annual
Accession No.
1031447
Grant No.
2023-51181-41156
Cumulative Award Amt.
$4,790,065.00
Proposal No.
2023-05661
Multistate No.
(N/A)
Project Start Date
Sep 1, 2023
Project End Date
Aug 31, 2027
Grant Year
2023
Program Code
[SCRI]- Specialty Crop Research Initiative
Project Director
Dutta, B.
Recipient Organization
UNIVERSITY OF GEORGIA
200 D.W. BROOKS DR
ATHENS,GA 30602-5016
Performing Department
(N/A)
Non Technical Summary
Anthracnose in watermelon and cucumber can severely impact yields and increase production costs in the absence of effective control options and is a threat to the long-term viability and profitability of the U.S. cucurbit industry. A coordinated, multi-state effort is required to improve our understanding of the recent anthracnose outbreaks by determining pathogen biology, population structure, host specificity, and fungicide resistance profiles of Colletotrichum spp. causing severe anthracnose outbreaks in cucurbit crops. This knowledge will lead to improved management strategies. Assessing the effects of specific production practices, environmental conditions, and inoculum on disease outbreaks can aid the development of practical, economically viable, and environmentally-sound strategies to limit yield losses due to anthracnose. Our team will address the pathogens (leverage genomics and population biology to identify theColletotrichumspecies complex(es) and inoculum sources), the host (screen commercial varieties and PI lines), and the environment (production practices) that constitute the disease triangle. We will integrate economic assessments and Extension efforts into each objective to further strengthen our project. This project meets the legislatively mandated SCRI focus areas of "efforts to identify and address threats from pests and diseases" and "efforts to improve production efficiency, handling and processing, productivity, and profitability."
Animal Health Component
60%
Research Effort Categories
Basic
40%
Applied
60%
Developmental
(N/A)
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
21614201102100%
Knowledge Area
216 - Integrated Pest Management Systems;

Subject Of Investigation
1420 - Melons;

Field Of Science
1102 - Mycology;
Goals / Objectives
Objective 1: Understand the pathogen population biology of emerging anthracnose epidemics of cucurbit crops in the eastern U.S. to improve management strategies. We will leverage genomics and population biology to identify the Colletotrichum species complex(es) involved in emerging watermelon and cucumber anthracnose epidemics in the eastern U.S.; determine the population genetic structure, host specificity, and fungicide resistance profile(s) of species involved; and develop PCR-based diagnostic tools for Colletotrichum species identification and detection of fungicide resistance against fungicide groups (QoI, MBC, DMI and SDHI) (45%).Objective 2: Identify effective production and management practices to prevent or reduce cucurbit anthracnose. We will examine how different sources of inoculum (seed and crop debris), production practices (e.g., including drip vs. overhead irrigation), fungicide programs, host response in varietal selections and core PI collections of watermelon and cucumber lines contribute to cucurbit anthracnose outbreaks; and develop pre- and post-harvest management programs that are environmentally and economically viable (55%).
Project Methods
Objective 1: Using standardized survey and isolation protocols, watermelon, cucumber, and other cucurbit crops (squash, cantaloupe) will be surveyed for anthracnose symptoms in seven eastern U.S. states representing more than 50% and 40% of the national watermelon and cucumber production, respectively (8-10 fields/state surveyed 2-3 times/season). Isolates collected will be used for the population biology and comparative genomics stuies. We will study pathogen species diversity using multilocus sequencing and pathogen population genetic structure and diversity using whole genome sequencing, single nucleotide polymorphism calling, and standard population genetic analyses. Host specificity and race-typing will be determined using a panel of cucurbit genotypes (watermelon, cucumber, squash, cantaloupe) in greenhouse bioassays. Resistance to QoI fungicides and development of molecular diagnostic assays for resistance and species identification will be determined using standard methods for plant-pathogenic fungi. Understanding the diversity and prevalence of Colletotrichum spp. as well as the QoI fungicide resistance profile in these regions will aid in development of practical methods, not only to detect Colletotrichum spp. but also to screen for QoI resistance within different populations.Objective 2: We will examine how seed-borne inoculum and production practices, including drip vs. overhead irrigation, fungicide programs, host response in varietal selections and core PI collection of watermelon and cucumber lines, and seed treatments, contribute toColletotrichumspp. outbreaks of cucurbit anthracnose and develop pre- and post-harvest management programs that are environmentally and economically viable. We will coordinate among seven eastern U.S. states (FL, GA, SC, NC, VA, DE and NY) and evaluate how production practices impact cucurbit anthracnose outbreaks: irrigation (type), selection of commercial cultivars (watermelon and cucumber) and fungicide programs. We will also coordinate with the CucCAP2 (SCRI PROPOSAL NO: 2020-51181-32139) group. This group has identified a panel of watermelon and cucumber breeding lines that are suitable for productivity and profitability; however, these lines have not been screened for cucurbit anthracnose. This project will provide an opportunity to screen these breeding lines along with other commercial cultivars, and the results will benefit both projects. The impact of cucurbit anthracnose on fruit yield, quality and marketability will be evaluated in replicated trial plots in FL, GA, SC, NC, VA, DE and NY. We will assess if debris and seeds play a role in anthracnose outbreaks in replicated field trials in watermelon and cucumber. We will further assess different crop debris management practices and seed treatments to reduce pathogen survival. We will conduct economic and stakeholder advisory panel assessments of regional trials each year that will enable us to determine the cost-benefit trade-off of recommended management strategies. Economic surveys through stakeholder engagement will be conducted to estimate the economic impact of cucurbit anthracnose on watermelon and cucumber growers. Standard extension platforms that will integrate feedback from the stakeholders will be used to disseminate outcomes of this project, which will ensure the highest likelihood of adoption.

Progress 09/01/23 to 08/31/24

Outputs
Target Audience:Primary audience of the project is the cucurbit producers in the easternUnited States. This includes watermelon and cucumber producers, packers, shippers, agronomists, crop consultants, farm managers, field workers, seed companies, and dealers; and watermelon and cucumberstorage and shipping/transport personnel and companies. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?Training opportunities were provided for postdocs, graduate students, and undergraduates in plant pathology, genomics, bioinformatics, and extension. These opportunities include conducting thesis or dissertation research, participating in computational, laboratory, greenhouse, or field projects, contributing to scientific or extension publications, and presenting findings to industry and scientific audiences. Undergraduate and graduate students learned to identify anthracnose symptoms on watermelon leaves and fruits, how to operate drip irrigation systems, how to select mature, ripe watermelons for harvest, and how to isolate pathogenic fungi from diseased plant samples and preserve them as purified cultures. How have the results been disseminated to communities of interest?Initial findings of the project were disseminated via various means including regional and state conferences and grower meetings. What do you plan to do during the next reporting period to accomplish the goals?We plan to make progress in activities listed for each objective and routinely disseminate findings via various outlets.

Impacts
What was accomplished under these goals? Standardized descriptive survey and isolation protocols: Protocols for survey and pathogen isolations were developed. In GA, we surveyed five commercial cucumber and three watermelon fields and collected over 150 isolates, which are currently in the process of being speciated and characterized for their pathogenicity and fungicide sensitivity. PD Dutta along with Co-PD Brewer and a post-doctoral associate Kaur has developed a PCR based assay for specific and sensitive detection of Colletotrichum orbiculare. Co-PI Queseda-Ocampo has also developed a semi-selective medium for selective recovery of C. orbiculare from plant samples. Co-PIs Roberts and Vallad surveyed commercial watermelon and cucumber fields in Florida and collected 39 isolates from six counties. Co-PI Queseda-Ocampo has collected 50 isolates from four commercial cucumber and watermelon fields in NC. Race-typing: Differential seeds were obtained and shared with other Co-PIs. A permit for Co-PI Roberts to receive out of state Colletotrichum isolates was submitted but has not yet been approved. Co-PI Roberts have completed germination testing and are now conducting the initial race-typing with a single-spored isolate from North Florida. Preliminary results are expected in October 2024. Determination of mutations underlying QoI (cytb), MBC (β-tubulin), SDHI (sdhB, sdhC, and sdhD) and DMI (cyp51) resistance: A rotating (4-week rotation) graduate student in Co-PD Brewer's lab has developed PCR primers for cytb based on the sequenced C. orbiculare 104T genome. The graduate student amplified and Sanger sequenced cytb for 9 isolates from watermelon, cantaloupe and cucumber with varying EC50 values for sensitivity to the QoI azoxystrobin. It was found that all watermelon isolates were wildtype at cytb, but all cucumber and cantaloupe isolates, which were generally less sensitive to azoxystrobin, had the F129L mutation known to provide partial resistance to QoIs. The PhD student who started August 10, 2024, will be developing an allele-specific PCR-based marker for this mutation and testing it on a panel of isolates from multiple states with varying EC50 values. Fungal population genomics: A postdoctoral researcher working on this objective joined the lab August 1, 2024. She has begun high quality DNA extractions for PacBio sequencing of select isolates. Evaluate the role of seedborne inoculum and seed-to-seedling transmission of C. orbiculare in anthracnose epidemics. Co-PI Walcott is optimizing DNA extraction protocol and a PCR assay to ensure the highest levels of C. orbicularedetection sensitivity and specificity from seed lots. In the interim, Co-PI Walcott is optimizing protocols for artificial seed infestation and seed-to-seedling transmission assays with C. orbiculare. Role of crop debris and field sanitation practices in reducing cucurbit anthracnose outbreaks.? To assess the role of crop debris and field sanitation practices in reducing cucurbit anthracnose outbreaks, field studies were initiated in Tifton, GA and Geneva, NY by Co-PIs Sintim and Pethybridge, respectively. The study entails three crop debris management systems: (a) crop debris left on the soil surface; (b) crop debris incorporated after harvesting; and (c) crop debris completely removed after harvest. The treatments were arranged in a randomized complete block design with four replications, and each treatment plot had three beds to ensure adequate buffer. All sampling and data collection will be made from the middle bed. The fields were planted to cucumber in Tifton and watermelon in Geneva, and the management systems (treatments) were imposed shortly after harvest in Tifton. The treatments will be imposed in mid-September in Geneva. Next year (2025), experimental plots will be planted to cucumber and watermelon, respectively in Tifton and Geneva, to assess treatment impact on cucurbit anthracnose control. This represents a worst-case scenario for anthracnose outbreak, given that growers would typically plant cucurbit in rotation with other crops. Therefore, a positive treatment response would reflect a very effective management system. We hypothesized that crop debris removal for cucurbit anthracnose control would not adversely impact soil health and overall carbon sequestration given the low residue biomass and rapid mineralization. Residues of fresh produce tend to mineralize rapidly because of the high moisture content and low C:N ratio. To test the above hypothesis, soil health assessment and soil carbon measurements were made before treatment imposition. Another assessment will be made in the final year of the study. Fungicide programs.PD-Dutta conducted two trials evaluating efficacy of 10 OMRI-listed products on managing anthracnose in watermelon and cucumber (Tifton, GA). None of the OMRI-listed products provided effective reduction in anthracnose severity compared to the non-treated control. Co-PIs Higgins and Langston conducting a 12-treatment single product fungicide efficacy trial in Painter, VA. Fungicide treatment is expected to be initiated in September and the trial is expected to be completed in October 2024. Co-PIs Higgins and Langston also conducting a 10-treatment commercial variety trial in Painter, VA. The trial is expected to be completed in October 2024. In SC, Co-PI Keinath conducted a fungicide efficacy trial with 10 fungicides and 2 non-treated controls. Despite inoculation of interplot spaces with a C. orbiculare race 2 isolate, anthracnose symptoms were found in only four plots. Data for disease severity were collected and are currently being analyzed. Co-PI Vallad conducted two field trials on cucumbers, evaluating ten conventional and ten biological fungicides. Limited separation between treatments and the untreated control was likely due to early-season herbicide damage. In the conventional trial, Cabrio (FRAC 11) showed superior performance. Evaluation of irrigation/leaf wetness. Co-PI Keinath in SC conducted a field trial with three leaf wetness treatments plus a non-treated control was set up and inoculated with a C. orbiculare race 2 isolate. Lengthening the leaf wetness periods with overhead misting at 6:00 a.m. and 6:00 p.m. significantly increased severity of anthracnose, but misting at noon did not. Evaluate host response in varietal selections and core PI collection of watermelon and cucumber lines.Co-PI Kousik has increased seeds for over 300 watermelon PI lines and around 220 cucumber PI lines. These seeds will be provided to breeders involved in this project for their evaluation in 2025 season. All these PI lines have been whole genome re-sequenced by CucCAP. Evaluation of commercial cultivars for anthracnose resistance is currently underway in GA, FL, VA, NY and DE. Data for disease severity and yield will be collected in September 2024. Economic analysis. In anticipation of the data from the project's first year of field experiment trials becoming ready for economic analysis in year two of the project, data collection began to acquire market prices for watermelon and cucumber across the different states considered in the project as well as input costs for products considered in the field trials. Additionally, a literature review was conducted for previous studies related to watermelon and cucumber conducting an economic analysis related to anthracnose management. Although there is a literature testing different management strategies for anthracnose, including different inputs and timing of management strategies, the literature has largely focused on the impact in disease rates, rather than the revenue-cost equation for producers.

Publications

  • Type: Websites Status: Published Year Published: 2024 Citation: https://site.extension.uga.edu/cucurbitanthracnose/sample-page/
  • Type: Conference Papers and Presentations Status: Other Year Published: 2024 Citation: Higgins, D.S. and Langston, D.L. 2024. Anthracnose, Downy Mildew, and Gummy Stem Blight Disease Management for Virginia Watermelons. Capron Area Watermelon Growers, Capron, VA.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2024 Citation: Dutta, B. 2024. Update on watermelon and cucumber anthracnose. Southeast Fruit and Vegetable Growers Conference, Savannah, GA.
  • Type: Other Status: Other Year Published: 2024 Citation: Dutta, B. 2024. Fungicide update on cucurbit anthracnose. Southeast Fruit and Vegetable Growers Conference, Savannah, GA.
  • Type: Conference Papers and Presentations Status: Other Year Published: 2024 Citation: Alshwaiki, G., Hagerty, A., Cochran S., Quesada-Ocampo L. M. 2024. Diversity of Fungal Plant Pathogens on North Carolina Cucumbers. Undergraduate Research and Creativity Symposium. NC State, Raleigh, NC.