Occurrence of the Conidial State of Erysiphe australiana on Crape Myrtle (Lagerstroemia indica) in Egypt

The plant genus Lagerstroemia, belongs to Family Lythraceae and consists of more than 50 species, is represented by only three species in Egypt. During 2012-2015, symptoms of powdery mildew were observed on shrubs of the Crape myrtle (Lagerstroemia indica L.) grown at the farm of the Fac. of Agric., Cairo Univ., Giza. The disease begins to appear during March and April. White superficial colonies, with abundant sporulation were developed on the infected leaves (Fig.1) as well as on the twigs and stems. As disease progress, the infected leaves are falling down. Naturally infected leaves were collected to identify the causal pathogen. Microscopic examinations revealed that conidiophores are unbranched and measured 40-73 X 4-10 μ. Foot cells are cylindrical. Conidia are ellipsoid or cylindrical, produced singly and measured 28-36 X 12-16 μ (Fig. 2). Ascocarps (The perfect stage) were not observed. Also, pathogenicity of the isolated fungus was confirmed in the Lab. of Plant Pathol. Dept., Fac. of Agric., Cairo Univ., using detached Crape myrtle leaves. On the basis of pathological and microscopical examinations, the causal fungus of Crape myrtle powdery mildew was identified as Erysiphe australiana (syn. Uncinuliella australiana). According to the available literatures, this is the first time to report
the conidial state of E. australiana on Crape myrtle in Egypt.