+ Site Statistics
References:
54,258,434
Abstracts:
29,560,870
PMIDs:
28,072,757
+ Search Articles
+ PDF Full Text Service
How our service works
Request PDF Full Text
+ Follow Us
Follow on Facebook
Follow on Twitter
Follow on LinkedIn
+ Subscribe to Site Feeds
Most Shared
PDF Full Text
+ Translate
+ Recently Requested

First Record of Thousand Cankers Disease Fungal Pathogen Geosmithia morbida and Walnut Twig Beetle Pityophthorus juglandis on Juglans regia in Europe



First Record of Thousand Cankers Disease Fungal Pathogen Geosmithia morbida and Walnut Twig Beetle Pityophthorus juglandis on Juglans regia in Europe



Plant Disease 98(10): 1445



Thousand cankers disease (TCD) is a disease complex caused by the fungus Geosmithia morbida Kolařik (Ascomycota, Hypocreales) and its vector Pityophthorus juglandis Blackman 1928 (Coleoptera, Scolytinae; walnut twig beetle, WTB). Since the mid-1990s, the disease was responsible for widespread mortality of many walnut species in the United States (4). After the first detection of TCD on black walnut (Juglans nigra L.) in Italy (3), an extensive survey was activated in cooperation with the Regional Phytosanitary Service. In May 2014, early TCD symptoms (4) were observed on English walnuts (J. regia L.). Canopies showed yellowing, wilting, and dieback of the youngest twigs, and a number of small brown cankers. Longitudinal and radial sections sampled through the cankers revealed gray to brown discoloration of both phloem and bark, and the presence of bark beetle galleries. Xylem discoloration was never observed. From one ~20-year-old European walnut growing in a garden neighboring an infected black walnut plantation (Santorso, Vicenza, 45°72' N, 11°40' E), a number of 1- to 2.5-cm-diameter twigs showing cankers up to 2 cm long surrounding bark beetle holes were collected. Whitish mycelium producing verticillate conidiophores was detected inside the insect galleries. From the necrotic margin of eight cankers previously surface-sterilized with 3% sodium hypochlorite, two 4-mm-wide chips per canker were placed on potato dextrose agar and incubated at 28 ± 1°C in the dark. Slow growing lobate, plane, yellowish-ocher colonies with hyaline mycelium appeared in 5 days. After subculturing to the same medium, growth features, mycelium, conidiophores, and conidia with morphological characteristics matching Kolarik's description of G. morbida (2) were observed. The ITS region of rDNA from the fungus strain LM14GM001-JR was amplified by using ITS1F and ITS4 primers and sequenced obtaining a 387-bp gene fragment. BLAST analysis showed 99% identity to the G. morbida strain U19 (GenBank Accession No. KF808301.1) for 384 bp, and 99% identity to the G. morbida strain LM13GM001-JN previously isolated from J. nigra in Italy (3). From the same samples, two emerging beetles were collected and identified as P. juglandis both morphologically (5) and genetically by DNA extraction following a standard salting out protocol. The barcode region of the mitochondrial gene cytochrome oxidase I was then amplified by using universal primers (1) and sequenced to obtain a 614-bp fragment of the gene. BLAST analysis showed 100% identity to P. juglandis based on comparison with KJ451422. A few other English walnuts with both the fungus and WTB were also found close to other infected black walnut plantations. To our knowledge, this is the first record of G. morbida and P. juglandis on J. regia in Europe, where the tree is cultivated for both fruit and timber production, as well as a traditional landscape tree. Voucher specimens are stored in the TeSAF herbarium and in the DAFNAE insect collection. References: (1) O. Folmer et al. Mol. Marine Biol. Biotechnol. 3:294, 1994. (2) M. Kolarik et al. Mycologia 103:325, 2011. (3) L. Montecchio and M. Faccoli. Plant Dis. 98:696, 2014. (4) S. J. Seybold et al. USDA Forest Service, NA-PR-02-10, 2013. (5) S. L. Wood. Great Basin Naturalist Memoirs 6:1123, 1982.

Please choose payment method:






(PDF emailed within 1 workday: $29.90)

Accession: 066446089

Download citation: RISBibTeXText

PMID: 30703957


Related references

First Record of Thousand Cankers Disease Geosmithia morbida and Walnut Twig Beetle Pityophthorus juglandis on Juglans nigra in Europe. Plant Disease 98(5): 696, 2019

Life history of the walnut twig beetle, Pityophthorus juglandis, and its association with Geosmithia morbida, causal agent of thousand cankers disease in the United States. Phytopathology 102(7): 159-159, 2012

Geosmithia morbida sp. nov., a new phytopathogenic species living in symbiosis with the walnut twig beetle (Pityophthorus juglandis) on Juglans in USA. Mycologia 103(2): 325-332, 2011

Geosmithia morbida sp. nov., a new phytopathogenic species living in symbiosis with the walnut twig beetle (Pityophthorus juglandis) on Juglans in Usa. Mycologia 103(2): 325-332, 2011

Wingnut (Juglandaceae) as a new generic host for Pityophthorus juglandis (Coleoptera: Curculionidae) and the thousand cankers disease pathogen, Geosmithia morbida (Ascomycota: Hypocreales). Canadian Entomologist 148(01): 83-91, 2016

Attraction of Walnut Twig Beetle Pityophthorus juglandis (Coleoptera: Curculionidae) to the Fungus Geosmithia morbida. Plant Health Progress 15(3): 135-140, 2014

Behavioral Responses of Pityophthorus juglandis (Coleoptera: Curculionidae: Scolytinae) to Volatiles of Black Walnut and Geosmithia morbida (Ascomycota: Hypocreales: Bionectriaceae), the Causal Agent of Thousand Cankers Disease. Environmental Entomology 47(2): 412-421, 2018

Phylogeography of the walnut twig beetle, Pityophthorus juglandis, the vector of thousand cankers disease in North American walnut trees. Plos One 10(2): E0118264-E0118264, 2016

Genetic differentiation and spatial structure of Geosmithia morbida, the causal agent of thousand cankers disease in black walnut (Juglans nigra). Current Genetics 60(2): 75-87, 2014

First Report of Geosmithia morbida in North Carolina: The Pathogen Involved in Thousand Cankers Disease of Black Walnut. Plant Disease 98(7): 992, 2019

An analysis of the larval instars of the walnut twig beetle, Pityophthorus juglandis Blackman Coleoptera Scolytidae, in northern California black walnut, Juglans hindsii, and a new host record for Hylocurus hirtellus. The Pan-Pacific Entomologist 88(2): 248-266, 2012

Population structure of Geosmithia morbida, the causal agent of Thousand cankers disease of walnut trees in the United States. Phytopathology 104(11): 135-135, 2014

Mycobiota associated with insect galleries in walnut with thousand cankers disease reveals a potential natural enemy against Geosmithia morbida. Fungal Biology 122(4): 241-253, 2018

Population structure of Geosmithia morbida, the causal agent of thousand cankers disease of walnut trees in the United States. Plos One 9(11): E112847, 2015

Life history and geographical distribution of the walnut twig beetle, Pityophthorus juglandis (Coleoptera: Scolytinae), in southern Europe. Journal of Applied Entomology 140(9): 697-705, 2016