دراسة بيولوجية للفطر (Erysiphe necator Schwein)‎ المسبب لمرض البياض الدقيقي على الكرمة في محافظة السويداء جنوبي سورية

الملخص EN

Grapevine powdery mildew caused by Erysiphe necator Schwein.

is one of the most important fungal diseases of the grapevine all over the world.

Due to the lack of local studies about the source of primary inoculum at the beginning of the season and the progression of the disease during the season, the aims of this study were to evaluate the incidence of grapevine powdery mildew and its biology on four local varieties cultivated in Sweida province (Syria) during 2015 and 2016.

The results showed that E.

necator survived as mycelium in grapevine dormant buds during winter to form “flag shoots” at the beginning of the season.

Although, cleistothecia were formed on infected leaves, but the ascospores may not have a significant role in the initiation of spring infection.The results showed also that the severity of the disease depended on the primary inoculum sources, the environmental conditions particularly frost, temperature, relative humidity, and the variety susceptibility.

It was shown that Balady and Black varieties were highly susceptible to powdery mildew on the leaves and clusters.

Salty variety was little susceptible, where symptoms have been observed on clusters holder only, while no symptoms were observed on Halwani variety, which seems to be the most resistant variety.