New Disease Reports
New Disease Reports (2007) 15, 11.
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First report of powdery mildew of Platanus orientalis caused by Erysiphe platani in China

C. Liang 1, G.Z. Lu 2 and H.D. Shin 3*

*hdshin@korea.ac.kr

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Accepted: 19 Feb 2007

In August 2006, Oriental plane trees (Platanus orientalis) exhibiting signs of powdery mildew were observed at Yunnan Agricultural University, Kunming, Yunnan province, South-Western China. In October 2006, powdery mildew infections also were found on leaves of roadside Oriental plane trees at Yantai, Shandong province, Eastern China. Further surveys in these two localities in November 2006 revealed chasmothecia associated with several lesions. Symptoms were characterised by chlorosis, distortion or cupping of young leaves (Fig. 1).

White superficial colonies developed amphigenously on leaves. Conidiophores, produced singly, were unbranched, cylindrical, 80-255 µm and were composed of 3-4(-5) cells. Conidia were ellipsoid or doliiform, 28-42 x 16-22 µm, with minutely reticulate surfaces (Fig. 2). Fibrosin bodies were absent. Chasmothecia were dark brown, spherical, scattered subgregariously, 90-125 µm diameter and contained several asci. Appendages arose equatorially, 6-18 per chasmothecium, were 1-1.7 times as long as the chasmothecial diameter, nearly straight, 7-8 µm wide, thick-walled at the base, gradually becoming narrower upward, 0-1-septate, compactly and irregularly branched 4-5 times at the apex (Fig. 3). Asci and ascospores were immature or could not be measured due to heavy infection by the hyperparasitic Ampelomyces quisqualis. We believe that this fungus is Erysiphe platani based on host genus, rather long conidiophores, conidia with ornamented walls, and gross morphological characteristics of the chasmothecia (Braun, 1987; Glawe, 2003).

Since Erysiphe platani first was recorded in the United States in 1874, it has been regarded as endemic in North America. From the second half of the 20th century, introduction and expansion of the range of this fungus to South America, South Africa, Australia and New Zealand, and European countries has been reported (Anselmi et al., 1994; Pastircakova, 2005, personal communication). Recently, the conidial state of this species was recorded on P. hispanica from Japan, the first time the fungus was reported in Asia (Tanda, 1999). Occurrence of this powdery mildew in two different, distantly separated parts of China suggests that this fungus is spreading in East Asia. Voucher specimens are deposited in the herbarium of Qingdao Agricultural University (HMLAC 06015, 06201, 06202).

Figure1+
Figure 1: Leaf of Platanus orientalis infected with Erysiphe platani
Figure 1: Leaf of Platanus orientalis infected with Erysiphe platani
Figure2+
Figure 2: Erysiphe platani. Conidia compared in different focus, displaying minutely reticulate cell walls (right) (Bar = 20 µm)
Figure 2: Erysiphe platani. Conidia compared in different focus, displaying minutely reticulate cell walls (right) (Bar = 20 µm)
Figure3+
Figure 3: Chasmothecia of Erysiphe platani (Bar = 100 µm)
Figure 3: Chasmothecia of Erysiphe platani (Bar = 100 µm)

References

  1. Anselmi N, Cardin L, Nicolotti G, 1994. Plane decline in European and Mediterranean countries: associated pests and their interactions. EPPO Bulletin 24, 159-171.
  2. Braun U, 1987. A Monograph of the Erysiphales (Powdery Mildews). Beihefte zur Nova Hedwigia 89, 1-700.
  3. Glawe DA, 2003. First report of powdery mildew of Platanus occidentalis caused by Microsphaera platani (Erysiphe platani) in Washington state. On-line. Plant Health Progress [http//www.plantmanagementnetwork.org/pub/php] doi:10.1094/PHP-2003-0818-01-HN.
  4. Tanda S, 1999. Powdery mildews on some ornamental trees and their causal fungi from Japan. Journal of Agricultural Science, Tokyo University of Agriculture 43, 253-259.
This report was formally published in Plant Pathology

©2007 The Authors