Seasonal trends in lethal bronzing phytoplasma infections from Florida, U.S.A. and its relationship to population phenology of Haplaxius crudus

Authors: BLOCK, MELODY - University Of Florida; HELMICK, ERICA - University Of Florida; LANE, JEREMY - University Of Florida; MOU, DE-FUN - University Of Florida; KOMONDY, LIDIA - University Of Florida; DILELLA, BRANDON - University Of Florida; Glover, James; GOSS, ERICA - University Of Florida; BAHDER, BRIAN - University Of Florida

Submitted to: Plant Health Progress
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/3/2026
Publication Date: N/A
Citation: N/A

Interpretive Summary: Farmers and agricultural producers rely on healthy crops and plants to stay profitable and continue supplying the food, fiber, and other plant based products people use every day. Research that helps prevent crop losses and improves pest and disease management directly supports the Secretary of Agriculture’s priority and the U.S. Department of Agriculture’s (USDA) goal of strengthening agricultural profitability. One disease causing major challenges in Florida is lethal bronzing, a destructive condition caused by a phytoplasma that spreads through plant feeding insects. Infected palms gradually turn brown and eventually die, creating financial losses for nurseries, landscapers, and communities while also serving as reservoirs that allow the disease to persist. To better understand how lethal bronzing spreads, scientists analyzed palm samples collected from 2017 to 2024 at the University of Florida’s Fort Lauderdale Research and Education Center. Their findings revealed a clear seasonal pattern: most new infections were detected between January and May, while the insect vector's activity peaks around September. Because infected palms are not detected immediately, there is a 4 to 8-month delay between infection and a positive test result. Recognizing this delay helps explain disease spread timing and improves predictions of when new infections will appear. With this knowledge, growers and land managers can better time monitoring and management efforts, reducing unnecessary treatments, saving resources, and protecting valuable plants, advancing the USDA’s broader mission to support effective plant health strategies that help farmers remain productive and profitable.

Technical Abstract: Lethal bronzing (LB) disease is a devastating phytoplasma disease that affects over 20 palm species. The disease is widespread in the state of Florida and causing significant economic losses to a variety of stakeholders that include nurseries, landscape companies, private homeowners, local municipalities and the state government. To aid stakeholders in managing LB on properties, palm samples are routinely screened for phytoplasma at the University of Florida Fort Lauderdale Research and Education Center (FLREC). While the priority of these data are to aid stakeholders, they also serve as a useful data collection tool that allow to better understand the epidemiology of the disease. In this study, data from 2017 to 2024 is assessed to better understand seasonal trends in new infections, especially in the context of vector populations. Over the period of eight years, a distinct seasonal trend is observed in number of positive detections of LB with the majority of positives occurring from January to May, significantly dropping from June to December. Populations of the vector were monitored and displayed peak activity in September. The relationship observed supports the observations of a four to eight month latent period where new infections begin to appear approximately four to eight months after peak vector activity. These data provide value insights into the epidemiology of LB in Florida and allow for a more precise timing of monitoring and management efforts.