Powdery Mildew Caused by Leveillula taurica (Synonym: Phyllactinia taurica): A Global Challenge for Pepper Production

Pepper powdery mildew, caused by the obligate fungal pathogen Leveillula taurica (asexual stage: Oidiopsis taurica (Lév.) Salmon 1906, synonym: Oidiopsis sicula Scalia 1902), poses a significant threat to pepper (Capsicum spp.) cultivation worldwide. This review delves into the taxonomy, geographical distribution, host range, disease symptoms, and life cycle of L. taurica and discusses strategies for managing its epidemics, with a focus on plant genetic immunity.

Phylum: Ascomycota; Class: Leotiomycetes; Order: Helotiales; Family: Erysiphaceae; Tribe: Phyllactinieae; Genus and species: Leveillula taurica (Lév.) Arnaud 1921. Synonym: Erysiphe taurica Léveillé 1851; in 2025, the species Leveillula taurica was renamed Phyllactinia taurica.

Leveillula taurica exhibits a broad host range, infecting monocotyledonous and dicotyledonous plants of around 200 genera across 60 families, including both herbaceous plants and trees. It causes substantial agricultural losses, particularly in pepper crops. The pathogen is distributed globally, occurring on all continents except Antarctica.

Initial symptoms include chlorotic spots on the upper leaf surface, which may coalesce and turn necrotic over time. A white mycelial coating (conidia and conidiophores) appears on the lower leaf surface beneath these spots. Severe infections can lead to leaf curling, defoliation, sunburned fruits and reduced yield and quality. The disease is particularly destructive in greenhouses and regions with hot, dry days alternating with cool, humid nights.

The hemi-endophytic lifestyle of L. taurica complicates disease management. Effective management of L. taurica involves integrated strategies: regular crop monitoring for early detection, cultural practices to limit fungal development, biocontrol agents, and chemical treatments to prevent or eradicate infections, and the use of resistant plant varieties. Sulphur-based fungicides, commonly used in organic farming, as well as demethylation inhibitors and quinone outside inhibitor (QoI) fungicides, have demonstrated efficacy; however, the emergence of QoI-resistant isolates necessitates cautious use. Additionally, biocontrol agents, such as Trichoderma spp. and other mycoparasitic fungi, provide alternative tools by inhibiting fungal growth. Breeding and deploying resistant varieties provide a sustainable approach to managing this disease.