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ARS Home » Northeast Area » Frederick, Maryland » Foreign Disease-Weed Science Research » Research » Publications at this Location » Publication #430129
Research Project: Discovery and Development of Microbial-Based Biological Control Agents for Use Against Invasive Weeds in the United States

Location: Foreign Disease-Weed Science Research

Title: Development of an early detection assay for monitoring the impact of the fungal biocontrol agent Ramularia crupinae on the noxious weed Crupina vulgaris

Author
item MCCAUSLIN, SYDNEY - Oak Ridge Institute For Science And Education (ORISE)
item Thomas, Jami
item SAWYER, COLE - Oak Ridge Institute For Science And Education (ORISE)
item DEVKOTA, SUDIKSHYA - University Of Idaho
item SCHWARZLÄNDER, MARK - University Of Idaho
item West, Natalie
item Fulcher, Michael
item Tancos, Matthew

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/23/2026
Publication Date: 2/2/2026
Citation: McCauslin, S., Thomas, J.L., Sawyer, C., Devkota, S., Schwarzländer, M., West, N.M., Fulcher, M.R., Tancos, M.A. 2026. Development of an early detection assay for monitoring the impact of the fungal biocontrol agent Ramularia crupinae on the noxious weed Crupina vulgaris. Plant Disease. https://doi.org/10.1094/PDIS-11-25-2352-RE.
DOI: https://doi.org/10.1094/PDIS-11-25-2352-RE

Interpretive Summary: Ramularia crupinae is the first biological control agent approved for the management of the federally noxious weed common crupina, which has invaded thousands of acres of grasslands in the western United States. A new diagnostic tool was developed to rapidly identify and track the recently released fungal agent R. crupinae. The development of this new diagnostic tool allows for the identification and tracking of R. crupinae following field release studies. The diagnostic assay is highly accurate, specific, and supports high-throughput processing of field samples, making it ideal for pathogen tracking and future impact studies. This new diagnostic tool will benefit researchers and land managers in tracking the establishment and spread of R. crupinae following its release, which is critical for measuring the agents’ impact on common crupina populations.

Technical Abstract: The fungal plant pathogen Ramularia crupinae is the first biological control agent approved for the management of the federally-listed noxious weed Crupina vulgaris (common crupina) in the United States. Widespread common crupina infestations threaten western U.S. rangelands and pastures by decreasing biodiversity and agricultural productivity through the displacement of native and beneficial plant species. This study reports the development of a sensitive and species-specific quantitative PCR (qPCR) diagnostic assay designed for tracking R. crupinae infections and monitoring impact following a field release. A unique group I intron located within the 18S ribosomal RNA region permitted the development of a specific and sensitive diagnostic assay capable of detecting R. crupinae in both symptomatic and asymptomatic common crupina tissue. Species-specificity was validated with no cross-reactivity against the closely related species R. acroptili and 47 common crupina fungal endophyte cultures collected from field samples prior to R. crupinae release. Serially diluted R. crupinae DNA was used to demonstrate a qPCR detection limit of 47 fg. This R. crupinae diagnostic assay is highly accurate and specific, does not require post-amplification visualization, and supports high-throughput processing of field samples, making it well suited for tracking R. crupinae establishment and spread. Monitoring R. crupinae movement is critical for studying the impact and epidemiology of this introduced biological control agent.