Erysiphales

Erysiphales is an order of ascomycete fungi that are commonly known as the powdery mildews. These fungi are obligate parasites of plants, meaning they require living host tissue to grow and reproduce. The order includes several genera that are significant plant pathogens, affecting a wide range of host plants.

Taxonomy

The order Erysiphales belongs to the class Leotiomycetes within the phylum Ascomycota. The family Erysiphaceae is the sole family within this order. The taxonomy of Erysiphales is primarily based on the morphology of the sexual and asexual reproductive structures.

Morphology

Erysiphales are characterized by their production of powdery, white to grayish mycelium on the surface of host plants. The asexual spores, known as conidia, are produced in chains on specialized hyphae called conidiophores. The sexual stage involves the formation of cleistothecia, which are closed fruiting bodies containing asci and ascospores.

Life Cycle

The life cycle of Erysiphales includes both asexual and sexual reproduction. During the growing season, the fungi primarily reproduce asexually through conidia, which are dispersed by wind to new host plants. In the sexual stage, cleistothecia develop and release ascospores, which can survive adverse conditions and germinate to infect new hosts in the following season.

Host Range and Symptoms

Erysiphales infect a wide variety of plants, including many economically important crops such as wheat, barley, grapevine, and cucurbits. Symptoms of infection include the characteristic powdery white spots on leaves, stems, and flowers, which can lead to reduced photosynthesis, stunted growth, and lower yields.

Control and Management

Management of powdery mildew involves a combination of cultural practices, resistant plant varieties, and chemical treatments. Cultural practices include proper spacing of plants to improve air circulation, removal of infected plant debris, and avoiding overhead irrigation. Fungicides are commonly used to control severe infections, but their use should be integrated with other management strategies to prevent the development of resistant fungal strains.

Notable Genera

Some notable genera within the order Erysiphales include:

• Erysiphe
• Blumeria
• Podosphaera
• Sphaerotheca

Research and Importance

Research on Erysiphales is important for understanding plant-pathogen interactions and developing effective control measures. The study of these fungi also contributes to the broader knowledge of fungal biology and ecology.

See Also

• Ascomycota
• Plant pathology
• Fungal diseases of plants