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Pamela S. Salvador Dutra wins the 2026 postdoctoral research poster competition 

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Woman in a black suit and tan trench coat standing with name tag at a conference, with a graphic of a mosquito.
Pamela S. Salvador Dutra, Ph.D., is a postdoctoral associate at the University of Florida. She secured first place in the EPI Research Day 2026 postdoctoral poster competition for her collaborative study, which explored how the fungus responsible for citrus black spot spreads through Florida citrus groves and canopies. (Photo credit: Brianne Lehan)

It was quite the day for University of Florida Institute of Food and Agricultural Sciences postdoctoral associate Pamela S. Salvador Dutra, Ph.D., as her name was announced as the first-place winner in the postdoctoral research poster competition. At the Emerging Pathogens Institute Research Day 2026, Salvador Dutra accepted the award on behalf of the Dewdney Lab for their dedicated work on fungal infections in the citrus industry.

Since 2024, Salvador Dutra has worked in the lab of Megan Dewdney, Ph.D., an EPI member, extension scientist and associate professor of plant pathology at the UF/IFAS Citrus Research and Education Center. The lab’s research focuses on the epidemiology of multiple plant pathogens, including Phyllosticta citricarpa, the fungal pathogen responsible for citrus black spot, or CBS. Since its detection in Florida in 2010, CBS has posed a significant challenge to the citrus industry. While the disease doesn’t change the fruit’s internal quality, it can seriously affect its appearance by covering it with black spots, making it less appealing in the market. It can also cause fruits to drop prematurely, leading to quarantine restrictions that make exporting fresh fruit more challenging in affected areas.

While some mystery remains regarding the pathogen’s behavior, leaf litter is the main source of infection. Globally, P. citricarpa reproduces sexually and asexually. The sexual form produces windborne ascospores, while the asexual form releases spores, known as conidia, spread by water splash over short distances. Ascospores are usually associated with outbreaks; however, sexual reproduction hasn’t been observed in the United States because mating types are absent. Florida’s outbreaks are driven solely by conidia, which, despite limited travel distance, are found throughout orchards and the canopy, raising questions about their upward movement from the orchard floor.

Close-up of an orange on a tree branch, visibly infected with Citrus Black Spot. The fruit’s surface is covered in numerous dark, circular blemishes. Other oranges and blurred foliage are visible in the background under a blue, cloudy sky.
Citrus black spot is a fungal disease that covers the outside of the fruit in black spots. (Photo courtesy of Pamela Salvador Dutra)

“Our goal is to understand how far conidia move vertically from the leaf litter into the canopy,” Salvador Dutra said. “Clarifying this component of the pathogen’s life cycle is essential for explaining disease spread and improving management strategies in Florida.”

To address these questions, the team conducted a field study in a CBS-affected sweet orange commercial grove in Felda, Florida. Monitoring pathogen movement weekly using rotating-arm spore traps, the team demonstrated that P. citricarpa conidia move upward efficiently through the canopy, with the pathogen detected from 0.15 m to 4.5 m (0.5 ft to 14.76 ft) above ground level. Detection was most frequent between 0.15 and 1 m (0.5 ft and 3.28 ft), pointing towards the orchard floor, specifically decomposing leaf litter, being the primary culprit behind conidia production.

“Our team did a great job,” said Salvador Dutra, who drove to the traps, collected the samples, and took them back to the lab to be analyzed. “This apparatus was built by a technician in our lab, a field technician. She did a great job. She installed all the motors, the electronic parts and the computer board.”

These results have direct, practical implications for growers. One of the most important takeaways from Salvador Dutra’s study is that effective CBS management must begin at ground level. Strategies that accelerate leaf-litter decomposition could reduce spore buildup and could help limit disease spread.

“Our study is only a screenshot of the full picture of understanding the biology of this pathogen,” Salvator Dutra said. “We are also incorporating detailed weather information to better understand the environmental conditions that influence conidia production, dispersal and subsequent disease development.”

This study was supported by USDA APHIS (AP24PPQS&T00C059).

Five people stand in a field looking up at a tall metal pole, with a red SUV parked to the left. The group, seen from the back, are surrounded by green trees and vegetation under a clear blue sky. They are standing on dirt and grass.
Salvador Dutra and the team traveled to the citrus groves to determine how the Citrus…
A woman squats beside a grey metal box with antennae attached, set within an orchard of citrus trees. The trees are full of green leaves and some fruit. The sky is blue with scattered white clouds. Grass and weeds grow in the foreground.
(Photo courtesy of Pamela Salvador Dutra)
A woman with blonde hair stands in an orange grove, wearing a blue and white baseball cap and a grey plaid shirt. She looks upward, holding a notebook and pen in one hand and reaching towards an orange on a tree branch with the other. Several oranges are visible among the green leaves.
(Photo courtesy of Pamela Salvador Dutra)

Monitoring Phyllosticta citricarpa vertical movement in citrus groves using rotating-arm spore traps

Collaborators

  • Pamela Suellen Salvador Dutra – College of Agricultural and Life Sciences, University of Florida
  • Tracey Hobbs – College of Agricultural and Life Sciences, University of Florida
  • Megan Dewdney – College of Agricultural and Life Sciences, University of Florida 

Abstract

Phyllosticta citricarpa, the causal agent of citrus black spot (CBS), is a federally regulated pathogen in Florida. While leaf litter is considered a primary inoculum source, upward dispersal of splash-borne conidia into the tree canopy is poorly understood. This study quantified DNA from conidia at multiple canopy heights in a commercial ‘Valencia’ sweet orange grove in southwest Florida, using rotating-arm spore traps. Three towers, each with nine traps, were placed adjacent to trees with severe CBS symptoms. Six traps were positioned vertically at 0.15, 1, 2, 3, 4, and 4.5 m facing the canopy, and three perpendicularly at 0.15, 1, and 2 m facing the alley. Each trap had a pair of rods that collected spores for 24 h during weekly sampling periods triggered by rainfall events (≥15 min) or during arbitrary 24-h periods when rain was absent. DNA was extracted from the rod surface, and qPCR was used to quantify P. citricarpa DNA. Trap height had a significant effect on both the detection likelihood and quantity of P. citricarpa DNA (p < 0.05). Although P. citricarpa was detected consistently at all trap heights, DNA quantities varied over the season, ranging from 1.5 to 3.1 femtograms/rod. P. citricarpa DNA detection was significantly higher in the lower canopy (0.15–1 m: 62% and 39%) compared to the intermediate canopy (2–3 m: 25% and 19%) and upper canopy heights (4–4.5 m: 19% and 22%). These results support leaf litter as a primary inoculum source and indicate upward conidia movement to the canopy, providing key aspects of pathogen biology necessary for optimizing CBS management.