Hybrid Protection Against Ergot (Claviceps purpurea (Fr.) Tul.) in Winter Rye (Secale cereale L.): Cultivar Susceptibility Under Artificial Inoculation and In Vitro Screening of Chemical, Biological and Botanical Agents

Abstract

Ergot, caused by Claviceps purpurea (Fr.) Tul., is a re-emerging disease that is particularly severe under wet weather during cereal flowering. It reduces grain quality and contaminates food and feed with toxic ergot alkaloids. Because no single measure reliably controls it, this study evaluated components of a hybrid protection approach for winter rye, coupling host-based control (cultivar susceptibility) with a panel of chemical, biological and botanical agents assessed in vitro against the pathogen. In a poisoned-medium (agar-dilution) assay, 11 treatments differed highly significantly in the suppression of mycelial growth. Complete inhibition (100%) was obtained with prothioconazole, mandestrobin, a systemic copper formulation, a Bacillus subtilis (QST 713) biocontrol product, mandarin essential oil (EO) (1% and 5%), and lemon and ginger EOs at 5%; azoxystrobin (83.6%) was intermediate, whereas ginger EO at 1% (74.8%) and lemon EO at 1% (30.2%) were significantly less inhibitory, with the EOs showing a clear dose response. In a field trial in which plots were artificially inoculated with a conidial suspension of the pathogen at anthesis, cultivar, location and year all significantly affected ergot content (p < 0.001; model R2 = 0.937), which ranged from 0.60% (cultivar DL 19) to 2.69% (cultivar SU Performer). Infestation was governed by a strong location × year interaction, yet a significant cultivar effect was detected within every location and year. Ergot content was very strongly correlated with ergot weight (r = 0.96) but not with yield, indicating that susceptibility was not linearly related to yield in this material and is a cultivar- and environment-driven trait relevant to integrated ergot management.