DISEASE NOTE FIRST REPORT OF POWDERY MILDEW CAUSED BY CYSTOTHECA LANESTRIS ON QUERCUS CRASSIPES IN MEXICO

Abstract

Red oak or Tuchi (Quercus crassipes) is an ornamental endemic species of Mexico. On November 9, 2016, powdery mildew was observed on leaves of Tuchi in Santa Fe, Mexico City. The symptoms and signs included deformed leaves, irregular necrotic lesions on both sides of the leaf, premature leaf drop, chasmothecia and mycelium. A reference specimen (CMPH-ECO23S) was deposited in the Herbarium of the Colegio de Postgraduados. The fungus produced light brown to dark reddish chasmothecia immersed in the mycelium. Chasmothecia were grouped or dispersed, 99-111 µm in diameter, composed of polygonal peridial cells of 12-18 µm; with simple, sinuous, poorly developed, short, or almost absent mycelial appendages (4-4.5 µm wide) that were interlaced with the surrounding mycelium. The single ascus was hyaline, ellipsoid or ovoid to globose, sessile, 80-91 x 55-68 µm to 134 x 85 µm. The ascospores were hyaline, ellipsoid to ovoid, 25-32 x 18-22 µm. Conidiophores and conidia were not observed. Amplification of ITS was carried out using primers ITS4 and ITS5. The PCR product (459 bp) was sequenced and deposited in GenBank (accession No. MF170000). The obtained sequence showed 100% similarity to AF011289 from Q. agrifolia. No ex-type sequence of C. lanestris is in GenBank, but the type and this sequence are from Q. agrifolia in California, USA. Based on morphological and molecular characteristics, the fungus observed on Quercus crassipes was identified as Cystotheca lanestris (Braun and Cook, 2012). To our knowledge, this is the first report of this fungus causing powdery mildew of red oak in Mexico. Braun U., Cook R.T.A., 2012. Taxonomic Manual of the Erysiphales (Powdery Mildews). CBS-KNAW

Full text

DISEASE NOTE
FIRST REPORT OF POWDERY MILDEW CAUSED BY
CYSTOTHECA LANESTRIS ON QUERCUS CRASSIPES IN
MEXICO
D. Cibrián-Tovar1, O.A. Pérez-Vera1 and C. Nava-Díaz2
1División de Ciencias Forestales (Departamento de Ecología y Silvicultura). Universidad
Autónoma Chapingo. Km 38.5 Carretera México-Texcoco, Chapingo, Texcoco, 56230. Estado
de México. México
2Fitopatología, Instituto de Fitosanidad, Campus Montecillo, Colegio de Postgraduados. Km
36.5 Carretera México-Texcoco, Montecillo, Texcoco, 56230. Estado de México, México
Red oak or Tuchi (Quercus crassipes) is an ornamental endemic species of Mexico. On
November 9, 2016, powdery mildew was observed on leaves of Tuchi in Santa Fe,
Mexico City. The symptoms and signs included deformed leaves, irregular necrotic
lesions on both sides of the leaf, premature leaf drop, chasmothecia and mycelium. A
reference specimen (CMPH-ECO23S) was deposited in the Herbarium of the Colegio
de Postgraduados. The fungus produced light brown to dark reddish chasmothecia
immersed in the mycelium. Chasmothecia were grouped or dispersed, 99-111 µm in
diameter, composed of polygonal peridial cells of 12-18 µm; with simple, sinuous,
poorly developed, short, or almost absent mycelial appendages (4-4.5 µm wide) that
were interlaced with the surrounding mycelium. The single ascus was hyaline, ellipsoid
or ovoid to globose, sessile, 80-91 x 55-68 µm to 134 x 85 µm. The ascospores were
hyaline, ellipsoid to ovoid, 25-32 x 18-22 µm. Conidiophores and conidia were not
observed. Amplification of ITS was carried out using primers ITS4 and ITS5. The PCR
product (459 bp) was sequenced and deposited in GenBank (accession No. MF170000).
The obtained sequence showed 100% similarity to AF011289 from Q. agrifolia. No ex-
type sequence of C. lanestris is in GenBank, but the type and this sequence are from Q.
agrifolia in California, USA. Based on morphological and molecular characteristics, the
fungus observed on Quercus crassipes was identified as Cystotheca lanestris (Braun
and Cook, 2012). To our knowledge, this is the first report of this fungus causing
powdery mildew of red oak in Mexico.
Braun U., Cook R.T.A., 2012. Taxonomic Manual of the Erysiphales (Powdery Mildews). CBS-
KNAW Fungal Biodiversity Centre. Utrecht, The Netherlands.
Journal of Plant Pathology

Corresponding author: O.A. Pérez-Vera
E-mail: oalejandrovera@gmail.com
Received June 22, 2017
Accepted August 28, 2017
Journal of Plant Pathology