Thousand cankers disease in Europe: an overview

Abstract

Walnut (Juglans regia L.) is traditionally present in most European countries as an ornamental tree, and in Southern Europe in particular it is grown for both fruit and wood. Since the 1980s, to supply the increasing demand for walnut timber, large areas of southern and central Europe, from France to Hungary, have been planted with black walnut (Juglans nigra L.) to provide wood for furniture production. The fungus Geosmithia morbida and its vector Pityophthorus juglandis, causing the thousand cankers disease of walnut in the USA in the last 2 decades, were recently reported in Europe (in Italy) on both walnut species. Thousand cankers disease can have a high negative impact on the landscape and economy of many agricultural and forest areas. Following a detailed pest risk analysis performed by EPPO in 2015, both organisms were included in the EPPO A2 List of pests recommended for regulation as quarantine pests. The main biological, epidemiological and monitoring aspects of thousand cankers disease and its status in Europe are reported.

A duplex real-time PCR with probe for simultaneous detection of Geosmithia morbida and its vector Pityophthorus juglandis

“…The disease, discovered in the EPPO region just a few years ago, is for the moment confined to Italy, the only foothold of TCD outside of North America. Here, the numerous, worrying sites, scattered throughout the north and, more recently, the center of the country, suggest the disease is rapidly expanding [ 19 , 25 ]. In spite of this alarming situation, studies on the bio-ecology, diagnosis, population dynamics, adaptation, as well as the management, of these two invasive alien species in the EPPO region are scarce.…”

“…In the autumn of 2013, both the pathogen and the vector were reported for the first time in Europe on several black walnut plantations at Bressanvido, Thiene and Schio, in the province of Vicenza, Veneto region, Italy [ 18 ]. Later, the disease was reported in four other Italian regions, Piedmont, Lombardy, Emilia-Romagna and Tuscany, whereas in a fifth Italian region, Friuli-Venezia-Giulia, only the vector was found [ 19 – 21 ]. A Pest Risk Analysis (PRA) carried out in 2015 scored the risk for a possible pervasive spread of TCD in the European and Mediterranean Plant Protection Organization (EPPO) area as “very high” [ 22 ].…”

A novel molecular toolkit for rapid detection of the pathogen and primary vector of thousand cankers disease

“…Our rapid molecular detection method will facilitate the detection of TCD organisms from new suspect sites and will aid in monitoring disease persistence in existing quarantine and buffer areas, thus mitigating further disease spread. Although regulatory quarantines can be effective, this measure has not prevented TCD from spreading across the USA and to Europe [ 12 , 20 , 46 ]. Lack of quarantine success could have been a consequence of a limited capability for detecting and restricting infected materials at borders and control points.…”

“…Currently, TCD has been reported in seven eastern U.S. states: Indiana, Maryland, North Carolina, Ohio, Pennsylvania, Tennessee, and Virginia [ 1 , 12 , 18 , 19 ]. TCD has also been reported in northern Italy [ 20 ], which is worrisome since this region is in the native range of J . regia [ 21 ]…”

The Effects of Weather on the Flight of an Invasive Bark Beetle, Pityophthorus juglandis

“…The walnut twig beetle, Pityophthorus juglandis Blackman (Coleoptera: Scolytidae), is an invasive pest that is native to the southwestern USA and Mexico [1,2]. It has expanded its distribution and occurs in nine western and seven eastern states in the USA [3][4][5][6] and in northern and central Italy [7][8][9]. Together with its symbiotic fungus, Geosmithia morbida M. Kolařík, E. Freeland, C. Utley, and N. Tisserat sp.…”