P-132 - Efficacy of chemical applications on the prevention of Vascular Streak Dieback (VSD) in redbud

Tuesday, August 5, 2025

9:30 AM - 10:15 AM HST

Location: Exhibit Hall 3

Presenting Author(s)

EW

Elizabeth L. White (she/her/hers)

Graduate Student
Purdue University, Department of Botany and Plant Pathology
Lafayette, Indiana, United States

Author(s)

JB

John Bonkowski

Principal Extension Administrator
Purdue University, Plant and Pest Diagnostic Laboratory
West Lafayette, Indiana, United States
TC

Tom Creswell

Clinical Engagement Professor
Purdue University, Plant and Pest Diagnostic Laboratory
West Lafayette, Indiana, United States
GM

Gerald L. Miller, Jr.

Extension Turfgrass Pathologist
Purdue University
West Lafayette, Indiana, United States

Abstract Text: Vascular streak dieback (VSD) is an emerging threat to the ornamental industry in the United States. Redbud (Cercis canadensis), maple (Acer spp.), and dogwood (Cornus spp.) are among the most heavily affected. VSD-symptomatic plants exhibit dieback, leaf chlorosis and necrosis, and necrotic streaks in the xylem. Isolations from symptomatic xylem tissue have consistently yielded the fungus Ceratobasidium sp. (Csp). Csp is closely related to the cacao pathogen Ceratobasidium theobromae (Ct). When infected with Ct, cacao exhibits similar symptoms to that of VSD-symptomatic woody ornamentals. Much is unknown about Csp and its link to VSD, and disease management recommendations are limited. The purpose of this research is to evaluate the efficacy of different fungicide products on the prevention of disease using natural inoculum in the field. At the Meigs Research Farm in West Lafayette, Indiana, healthy redbud saplings were planted in a completely randomized design underneath mature VSD-positive redbuds and sprayed with different commercial products. Foliar symptom progression was monitored from May 2024 to October 2024. A two-way ANOVA at α = 0.05 yielded no statistical difference between treatments groups or observation date with any disease progression parameters. No Csp DNA was detected in petiole tissue, suggesting a lack of Csp infection. Applications and observations will continue for a second season, and final Csp infection will be determined from DNA extractions and subsequent amplification of Ceratobasidium specific sequences of leaf, petiole, and stem tissue.