Effect of Sterol Biosynthesis Inhibitors and Azole-Type Inducers on Growth and Development of Plasmopara Viticola on Grapevine

The study investigated the impact of azole fungicides and sterol biosynthesis inhibitors on the growth and development of Plasmopara viticola, the pathogen responsible for downy mildew in grapevines. It was found that applying demethylation inhibitors (DMIs) and azole-type inducers two days before inoculation delayed mycelial growth initially but did not affect it after five to seven days, nor did it significantly reduce sporulation when applied during or after inoculation. However, inhibiting plant brassinosteroid biosynthesis with finasteride significantly reduced sporulation, suggesting that plant-derived sterols or sterol-modulated processes play a role in pathogen reproduction.