First report of <i>Erysiphe australiana</i> from Uzbekistan
Annotatsiya
Lagerstroemia indica is a widely grown ornamental shrub or small tree that has become naturalised and invasive in many tropical and subtropical regions of the world. Lagerstroemia indica is often used to provide shade around parking areas, for median strip plantings along roads, and is also planted in domestic gardens (CABI, 2019). The tree was introduced in 2007 to improve landscaping in Tashkent, Uzbekistan. Between August and October 2020, powdery mildew symptoms were observed on leaves and twigs of L. indica in parks and green areas of Tashkent. Symptoms were more prominent on young leaves and twigs compared with older leaves and twigs. Samples were collected from the affected parts of the trees and either used fresh or stored dry as herbarium material until analysis, as described by Heluta (1989). Herbarium specimens (TASM 9001, TASM 9002, TASM 9003, TASM 9004) were deposited in the Tashkent Mycological herbarium (TASM) of the Institute of Botany of Academy of Sciences, Republic of Uzbekistan. Dense white effuse, amphigenous mycelial patches were present on the leaves and inflorescences (Fig. 1). Chasmothecia, conidiophores and conidia were observed and measured in oil immersion, using a Moticam 5N-300M microscope at a magnification up to ×400. Conidiophores were erect, hyaline, and measured 56–85 × 7–10 μm. Foot cells were cylindrical, sometimes slightly flexuous, followed by 1–2 shorter cells. Conidia were formed singly, cylindrical to ellipsoid, hyaline, 28–35 × 14–21 μm. Fibrosin bodies were absent. Chasmothecia scattered, brown, 55 – 60 μm diameter, appendages equatorial, flexuous, 75–80 μm long, hyaline, walls thin, smooth, apices loosely or tightly uncinate˗circinate, not enlarged (Fig. 2). Based on morphological analyses, the pathogen was identified as Erysiphe australiana. This disease of L. indica develops mainly in August and September in Uzbekistan, making affected plants unsightly with heavy defoliation and twisted leaves. Defoliation and death of young shoots often results. To our knowledge, this is the first report of powdery mildew of L. indica in Uzbekistan. The species has been reported previously on Lagerstroemia spp. in Argentina (Delhey et al., 2003) and more recently in Turkey (Göre, 2009) and India (Baiswar et al., 2009).