Evaluation of Coniothyrium minitans as a Mycoparasite of Sclerotinia sclerotiorum in Sunflower Under Field Conditions

Abstract

Evaluation of Coniothyrium minitans as a mycoparasite of Sclerotinia sclerotiorum in sunflower was conducted under field conditions to assess its potential as a biological control agent against white mold disease. Field trials were established in sunflower plots with a known history of S. sclerotiorum incidence, and C. minitans formulations were applied to soil and crop residues prior to pathogen establishment. Disease incidence, severity index, sclerotial density, and sunflower yield parameters were recorded to determine treatment efficacy. Results indicated that application of C. minitans significantly reduced the viability and germination of S. sclerotiorum sclerotia in soil, thereby lowering disease pressure in treated plots. Treated sunflower plants exhibited reduced stem rot incidence and improved growth performance compared to untreated controls. The mycoparasite established effectively in the rhizosphere and demonstrated persistent antagonistic activity against the pathogen under field environmental conditions. Observations suggested that C. minitans acts through direct parasitism of sclerotia, reducing inoculum survival and interrupting the disease cycle. Enhanced crop yield in treated plots further confirmed its effectiveness as a biological control agent. The study highlights the potential of C. minitans as a sustainable and environmentally friendly alternative to chemical fungicides for managing white mold in sunflower. These findings support its integration into disease management programs through soil amendment and crop residue management strategies.